Simplify $frac {sec^2theta - cos^2theta}{tan^2theta}$
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My question is to simplify:$$frac {sec^2theta - cos^2theta}{tan^2theta}$$
My workings:
$$frac {sec^2theta - cos^2theta}{tan^2theta}=frac {frac {1}{cos^2theta}- cos^2theta} {tan^2theta}$$
Then I am unable to continue, can someone please show me some working outs? Thank you.
trigonometry
add a comment |
up vote
0
down vote
favorite
My question is to simplify:$$frac {sec^2theta - cos^2theta}{tan^2theta}$$
My workings:
$$frac {sec^2theta - cos^2theta}{tan^2theta}=frac {frac {1}{cos^2theta}- cos^2theta} {tan^2theta}$$
Then I am unable to continue, can someone please show me some working outs? Thank you.
trigonometry
1
$$dfrac{1}{cos^2t}-cos^2t=dfrac{1-cos^4t}{cos^2t}=dfrac{(1-cos^2t)(1+cos^2t)}{cos^2t}=dfrac{(sin^2t)(1+cos^2t)}{cos^2t}=tan^2t(1+cos^2t)$$
– Nosrati
Nov 23 at 7:15
$dfrac{1/c^2-c^2}{s^2/c^2}=dfrac{1-c^4}{s^2}=1+c^2$
– Narasimham
Nov 24 at 15:38
add a comment |
up vote
0
down vote
favorite
up vote
0
down vote
favorite
My question is to simplify:$$frac {sec^2theta - cos^2theta}{tan^2theta}$$
My workings:
$$frac {sec^2theta - cos^2theta}{tan^2theta}=frac {frac {1}{cos^2theta}- cos^2theta} {tan^2theta}$$
Then I am unable to continue, can someone please show me some working outs? Thank you.
trigonometry
My question is to simplify:$$frac {sec^2theta - cos^2theta}{tan^2theta}$$
My workings:
$$frac {sec^2theta - cos^2theta}{tan^2theta}=frac {frac {1}{cos^2theta}- cos^2theta} {tan^2theta}$$
Then I am unable to continue, can someone please show me some working outs? Thank you.
trigonometry
trigonometry
edited Nov 23 at 7:27
Jean-Claude Arbaut
14.7k63363
14.7k63363
asked Nov 23 at 7:13
Tfue
859
859
1
$$dfrac{1}{cos^2t}-cos^2t=dfrac{1-cos^4t}{cos^2t}=dfrac{(1-cos^2t)(1+cos^2t)}{cos^2t}=dfrac{(sin^2t)(1+cos^2t)}{cos^2t}=tan^2t(1+cos^2t)$$
– Nosrati
Nov 23 at 7:15
$dfrac{1/c^2-c^2}{s^2/c^2}=dfrac{1-c^4}{s^2}=1+c^2$
– Narasimham
Nov 24 at 15:38
add a comment |
1
$$dfrac{1}{cos^2t}-cos^2t=dfrac{1-cos^4t}{cos^2t}=dfrac{(1-cos^2t)(1+cos^2t)}{cos^2t}=dfrac{(sin^2t)(1+cos^2t)}{cos^2t}=tan^2t(1+cos^2t)$$
– Nosrati
Nov 23 at 7:15
$dfrac{1/c^2-c^2}{s^2/c^2}=dfrac{1-c^4}{s^2}=1+c^2$
– Narasimham
Nov 24 at 15:38
1
1
$$dfrac{1}{cos^2t}-cos^2t=dfrac{1-cos^4t}{cos^2t}=dfrac{(1-cos^2t)(1+cos^2t)}{cos^2t}=dfrac{(sin^2t)(1+cos^2t)}{cos^2t}=tan^2t(1+cos^2t)$$
– Nosrati
Nov 23 at 7:15
$$dfrac{1}{cos^2t}-cos^2t=dfrac{1-cos^4t}{cos^2t}=dfrac{(1-cos^2t)(1+cos^2t)}{cos^2t}=dfrac{(sin^2t)(1+cos^2t)}{cos^2t}=tan^2t(1+cos^2t)$$
– Nosrati
Nov 23 at 7:15
$dfrac{1/c^2-c^2}{s^2/c^2}=dfrac{1-c^4}{s^2}=1+c^2$
– Narasimham
Nov 24 at 15:38
$dfrac{1/c^2-c^2}{s^2/c^2}=dfrac{1-c^4}{s^2}=1+c^2$
– Narasimham
Nov 24 at 15:38
add a comment |
2 Answers
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oldest
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up vote
3
down vote
accepted
$$frac{sec^2 theta-cos^2 theta}{tan^2 theta}$$
$$=frac{frac{1}{cos^2 theta}-cos^2 theta}{tan^2 theta}$$
From here, use the common denominator $cos^2 theta$.
$$=frac{frac{1}{cos^2 theta}-frac{cos^4 theta}{cos^2 theta}}{tan^2 theta}$$
$$=frac{frac{1-cos^4 theta}{cos^2 theta}}{tan^2 theta} = frac{frac{(1-cos^2 theta)(1+cos^2 theta)}{cos^2 theta}}{tan^2 theta} = frac{frac{(1-cos^2 theta)(1+cos^2 theta)}{cos^2 theta}}{frac{sin^2 theta}{cos^2 theta}} = frac{{(1-cos^2 theta)(1+cos^2 theta)}}{sin^2 theta}$$
Recall $1-cos^2theta = sin^2 theta$.
$$= frac{{(sin^2 theta)(1+cos^2 theta)}}{sin^2 theta} = 1+cos^2 theta$$
Wow extremely insightful solution! But i have 1 question, what is the technique when you expand the $1-cos^4theta$
– Tfue
Nov 23 at 7:27
1
You mean when I factored it to get $(1-cos^2 theta)(1-sin^2 theta)$? If so, that is simply using the difference of squares. It is helpful to remember that $a^2-b^2 = (a+b)(a-b)$.
– KM101
Nov 23 at 7:28
So i view $b$ as $cos^2theta$ in this case? And does this apply in every cases?
– Tfue
Nov 23 at 7:30
Yes to both questions. Of course, as gimusi said, there are many ways (which are essentially equivalent) to simplify trig expressions since there are many definitions and base identities which lead to the same answer. It's good to use whatever way you find simplest.
– KM101
Nov 23 at 7:33
add a comment |
up vote
3
down vote
For $cos theta neq 0$ we have
$$frac {cos^2theta}{cos^2theta}cdot frac {frac {1}{cos^2theta}- cos^2theta} {tan^2theta}=frac{1-cos^4 theta}{sin^2theta}=frac{(1-cos^2 theta)(1+cos^2 theta)}{1-cos^2 theta}=1+cos^2 theta$$
Hey thanks! but why did you times $frac {cos^2theta}{cos^2theta}$ to the equation, how does it works and can you do that? Also can i apply your technique in all cases?
– Tfue
Nov 23 at 7:23
2
@Tfue We can do that since it is equal to 1 and for the definition of the expression we are assuming $cos theta neq 0$.
– gimusi
Nov 23 at 7:24
1
You can divide/multiply both the numerator and denominator by $cos theta$ to rewrite the expression in a form that can be simplified more easily. (Essentially, you're multiplying/dividing by $1$, so it is equivalent to the original expression.)
– KM101
Nov 23 at 7:25
1
@Tfue Of course we can proceed in many others equivalent ways, for example $$frac {frac {1}{cos^2theta}- cos^2theta} {tan^2theta}=frac {frac {1}{cos^2theta}- cos^2theta} {frac{sin^2theta}{cos^2theta}}=frac{cos^2theta}{sin^2theta}left(frac {1}{cos^2theta}- cos^2thetaright)=ldots$$
– gimusi
Nov 23 at 7:27
add a comment |
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2 Answers
2
active
oldest
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2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
3
down vote
accepted
$$frac{sec^2 theta-cos^2 theta}{tan^2 theta}$$
$$=frac{frac{1}{cos^2 theta}-cos^2 theta}{tan^2 theta}$$
From here, use the common denominator $cos^2 theta$.
$$=frac{frac{1}{cos^2 theta}-frac{cos^4 theta}{cos^2 theta}}{tan^2 theta}$$
$$=frac{frac{1-cos^4 theta}{cos^2 theta}}{tan^2 theta} = frac{frac{(1-cos^2 theta)(1+cos^2 theta)}{cos^2 theta}}{tan^2 theta} = frac{frac{(1-cos^2 theta)(1+cos^2 theta)}{cos^2 theta}}{frac{sin^2 theta}{cos^2 theta}} = frac{{(1-cos^2 theta)(1+cos^2 theta)}}{sin^2 theta}$$
Recall $1-cos^2theta = sin^2 theta$.
$$= frac{{(sin^2 theta)(1+cos^2 theta)}}{sin^2 theta} = 1+cos^2 theta$$
Wow extremely insightful solution! But i have 1 question, what is the technique when you expand the $1-cos^4theta$
– Tfue
Nov 23 at 7:27
1
You mean when I factored it to get $(1-cos^2 theta)(1-sin^2 theta)$? If so, that is simply using the difference of squares. It is helpful to remember that $a^2-b^2 = (a+b)(a-b)$.
– KM101
Nov 23 at 7:28
So i view $b$ as $cos^2theta$ in this case? And does this apply in every cases?
– Tfue
Nov 23 at 7:30
Yes to both questions. Of course, as gimusi said, there are many ways (which are essentially equivalent) to simplify trig expressions since there are many definitions and base identities which lead to the same answer. It's good to use whatever way you find simplest.
– KM101
Nov 23 at 7:33
add a comment |
up vote
3
down vote
accepted
$$frac{sec^2 theta-cos^2 theta}{tan^2 theta}$$
$$=frac{frac{1}{cos^2 theta}-cos^2 theta}{tan^2 theta}$$
From here, use the common denominator $cos^2 theta$.
$$=frac{frac{1}{cos^2 theta}-frac{cos^4 theta}{cos^2 theta}}{tan^2 theta}$$
$$=frac{frac{1-cos^4 theta}{cos^2 theta}}{tan^2 theta} = frac{frac{(1-cos^2 theta)(1+cos^2 theta)}{cos^2 theta}}{tan^2 theta} = frac{frac{(1-cos^2 theta)(1+cos^2 theta)}{cos^2 theta}}{frac{sin^2 theta}{cos^2 theta}} = frac{{(1-cos^2 theta)(1+cos^2 theta)}}{sin^2 theta}$$
Recall $1-cos^2theta = sin^2 theta$.
$$= frac{{(sin^2 theta)(1+cos^2 theta)}}{sin^2 theta} = 1+cos^2 theta$$
Wow extremely insightful solution! But i have 1 question, what is the technique when you expand the $1-cos^4theta$
– Tfue
Nov 23 at 7:27
1
You mean when I factored it to get $(1-cos^2 theta)(1-sin^2 theta)$? If so, that is simply using the difference of squares. It is helpful to remember that $a^2-b^2 = (a+b)(a-b)$.
– KM101
Nov 23 at 7:28
So i view $b$ as $cos^2theta$ in this case? And does this apply in every cases?
– Tfue
Nov 23 at 7:30
Yes to both questions. Of course, as gimusi said, there are many ways (which are essentially equivalent) to simplify trig expressions since there are many definitions and base identities which lead to the same answer. It's good to use whatever way you find simplest.
– KM101
Nov 23 at 7:33
add a comment |
up vote
3
down vote
accepted
up vote
3
down vote
accepted
$$frac{sec^2 theta-cos^2 theta}{tan^2 theta}$$
$$=frac{frac{1}{cos^2 theta}-cos^2 theta}{tan^2 theta}$$
From here, use the common denominator $cos^2 theta$.
$$=frac{frac{1}{cos^2 theta}-frac{cos^4 theta}{cos^2 theta}}{tan^2 theta}$$
$$=frac{frac{1-cos^4 theta}{cos^2 theta}}{tan^2 theta} = frac{frac{(1-cos^2 theta)(1+cos^2 theta)}{cos^2 theta}}{tan^2 theta} = frac{frac{(1-cos^2 theta)(1+cos^2 theta)}{cos^2 theta}}{frac{sin^2 theta}{cos^2 theta}} = frac{{(1-cos^2 theta)(1+cos^2 theta)}}{sin^2 theta}$$
Recall $1-cos^2theta = sin^2 theta$.
$$= frac{{(sin^2 theta)(1+cos^2 theta)}}{sin^2 theta} = 1+cos^2 theta$$
$$frac{sec^2 theta-cos^2 theta}{tan^2 theta}$$
$$=frac{frac{1}{cos^2 theta}-cos^2 theta}{tan^2 theta}$$
From here, use the common denominator $cos^2 theta$.
$$=frac{frac{1}{cos^2 theta}-frac{cos^4 theta}{cos^2 theta}}{tan^2 theta}$$
$$=frac{frac{1-cos^4 theta}{cos^2 theta}}{tan^2 theta} = frac{frac{(1-cos^2 theta)(1+cos^2 theta)}{cos^2 theta}}{tan^2 theta} = frac{frac{(1-cos^2 theta)(1+cos^2 theta)}{cos^2 theta}}{frac{sin^2 theta}{cos^2 theta}} = frac{{(1-cos^2 theta)(1+cos^2 theta)}}{sin^2 theta}$$
Recall $1-cos^2theta = sin^2 theta$.
$$= frac{{(sin^2 theta)(1+cos^2 theta)}}{sin^2 theta} = 1+cos^2 theta$$
answered Nov 23 at 7:22
KM101
3,777417
3,777417
Wow extremely insightful solution! But i have 1 question, what is the technique when you expand the $1-cos^4theta$
– Tfue
Nov 23 at 7:27
1
You mean when I factored it to get $(1-cos^2 theta)(1-sin^2 theta)$? If so, that is simply using the difference of squares. It is helpful to remember that $a^2-b^2 = (a+b)(a-b)$.
– KM101
Nov 23 at 7:28
So i view $b$ as $cos^2theta$ in this case? And does this apply in every cases?
– Tfue
Nov 23 at 7:30
Yes to both questions. Of course, as gimusi said, there are many ways (which are essentially equivalent) to simplify trig expressions since there are many definitions and base identities which lead to the same answer. It's good to use whatever way you find simplest.
– KM101
Nov 23 at 7:33
add a comment |
Wow extremely insightful solution! But i have 1 question, what is the technique when you expand the $1-cos^4theta$
– Tfue
Nov 23 at 7:27
1
You mean when I factored it to get $(1-cos^2 theta)(1-sin^2 theta)$? If so, that is simply using the difference of squares. It is helpful to remember that $a^2-b^2 = (a+b)(a-b)$.
– KM101
Nov 23 at 7:28
So i view $b$ as $cos^2theta$ in this case? And does this apply in every cases?
– Tfue
Nov 23 at 7:30
Yes to both questions. Of course, as gimusi said, there are many ways (which are essentially equivalent) to simplify trig expressions since there are many definitions and base identities which lead to the same answer. It's good to use whatever way you find simplest.
– KM101
Nov 23 at 7:33
Wow extremely insightful solution! But i have 1 question, what is the technique when you expand the $1-cos^4theta$
– Tfue
Nov 23 at 7:27
Wow extremely insightful solution! But i have 1 question, what is the technique when you expand the $1-cos^4theta$
– Tfue
Nov 23 at 7:27
1
1
You mean when I factored it to get $(1-cos^2 theta)(1-sin^2 theta)$? If so, that is simply using the difference of squares. It is helpful to remember that $a^2-b^2 = (a+b)(a-b)$.
– KM101
Nov 23 at 7:28
You mean when I factored it to get $(1-cos^2 theta)(1-sin^2 theta)$? If so, that is simply using the difference of squares. It is helpful to remember that $a^2-b^2 = (a+b)(a-b)$.
– KM101
Nov 23 at 7:28
So i view $b$ as $cos^2theta$ in this case? And does this apply in every cases?
– Tfue
Nov 23 at 7:30
So i view $b$ as $cos^2theta$ in this case? And does this apply in every cases?
– Tfue
Nov 23 at 7:30
Yes to both questions. Of course, as gimusi said, there are many ways (which are essentially equivalent) to simplify trig expressions since there are many definitions and base identities which lead to the same answer. It's good to use whatever way you find simplest.
– KM101
Nov 23 at 7:33
Yes to both questions. Of course, as gimusi said, there are many ways (which are essentially equivalent) to simplify trig expressions since there are many definitions and base identities which lead to the same answer. It's good to use whatever way you find simplest.
– KM101
Nov 23 at 7:33
add a comment |
up vote
3
down vote
For $cos theta neq 0$ we have
$$frac {cos^2theta}{cos^2theta}cdot frac {frac {1}{cos^2theta}- cos^2theta} {tan^2theta}=frac{1-cos^4 theta}{sin^2theta}=frac{(1-cos^2 theta)(1+cos^2 theta)}{1-cos^2 theta}=1+cos^2 theta$$
Hey thanks! but why did you times $frac {cos^2theta}{cos^2theta}$ to the equation, how does it works and can you do that? Also can i apply your technique in all cases?
– Tfue
Nov 23 at 7:23
2
@Tfue We can do that since it is equal to 1 and for the definition of the expression we are assuming $cos theta neq 0$.
– gimusi
Nov 23 at 7:24
1
You can divide/multiply both the numerator and denominator by $cos theta$ to rewrite the expression in a form that can be simplified more easily. (Essentially, you're multiplying/dividing by $1$, so it is equivalent to the original expression.)
– KM101
Nov 23 at 7:25
1
@Tfue Of course we can proceed in many others equivalent ways, for example $$frac {frac {1}{cos^2theta}- cos^2theta} {tan^2theta}=frac {frac {1}{cos^2theta}- cos^2theta} {frac{sin^2theta}{cos^2theta}}=frac{cos^2theta}{sin^2theta}left(frac {1}{cos^2theta}- cos^2thetaright)=ldots$$
– gimusi
Nov 23 at 7:27
add a comment |
up vote
3
down vote
For $cos theta neq 0$ we have
$$frac {cos^2theta}{cos^2theta}cdot frac {frac {1}{cos^2theta}- cos^2theta} {tan^2theta}=frac{1-cos^4 theta}{sin^2theta}=frac{(1-cos^2 theta)(1+cos^2 theta)}{1-cos^2 theta}=1+cos^2 theta$$
Hey thanks! but why did you times $frac {cos^2theta}{cos^2theta}$ to the equation, how does it works and can you do that? Also can i apply your technique in all cases?
– Tfue
Nov 23 at 7:23
2
@Tfue We can do that since it is equal to 1 and for the definition of the expression we are assuming $cos theta neq 0$.
– gimusi
Nov 23 at 7:24
1
You can divide/multiply both the numerator and denominator by $cos theta$ to rewrite the expression in a form that can be simplified more easily. (Essentially, you're multiplying/dividing by $1$, so it is equivalent to the original expression.)
– KM101
Nov 23 at 7:25
1
@Tfue Of course we can proceed in many others equivalent ways, for example $$frac {frac {1}{cos^2theta}- cos^2theta} {tan^2theta}=frac {frac {1}{cos^2theta}- cos^2theta} {frac{sin^2theta}{cos^2theta}}=frac{cos^2theta}{sin^2theta}left(frac {1}{cos^2theta}- cos^2thetaright)=ldots$$
– gimusi
Nov 23 at 7:27
add a comment |
up vote
3
down vote
up vote
3
down vote
For $cos theta neq 0$ we have
$$frac {cos^2theta}{cos^2theta}cdot frac {frac {1}{cos^2theta}- cos^2theta} {tan^2theta}=frac{1-cos^4 theta}{sin^2theta}=frac{(1-cos^2 theta)(1+cos^2 theta)}{1-cos^2 theta}=1+cos^2 theta$$
For $cos theta neq 0$ we have
$$frac {cos^2theta}{cos^2theta}cdot frac {frac {1}{cos^2theta}- cos^2theta} {tan^2theta}=frac{1-cos^4 theta}{sin^2theta}=frac{(1-cos^2 theta)(1+cos^2 theta)}{1-cos^2 theta}=1+cos^2 theta$$
answered Nov 23 at 7:17
gimusi
92.3k84495
92.3k84495
Hey thanks! but why did you times $frac {cos^2theta}{cos^2theta}$ to the equation, how does it works and can you do that? Also can i apply your technique in all cases?
– Tfue
Nov 23 at 7:23
2
@Tfue We can do that since it is equal to 1 and for the definition of the expression we are assuming $cos theta neq 0$.
– gimusi
Nov 23 at 7:24
1
You can divide/multiply both the numerator and denominator by $cos theta$ to rewrite the expression in a form that can be simplified more easily. (Essentially, you're multiplying/dividing by $1$, so it is equivalent to the original expression.)
– KM101
Nov 23 at 7:25
1
@Tfue Of course we can proceed in many others equivalent ways, for example $$frac {frac {1}{cos^2theta}- cos^2theta} {tan^2theta}=frac {frac {1}{cos^2theta}- cos^2theta} {frac{sin^2theta}{cos^2theta}}=frac{cos^2theta}{sin^2theta}left(frac {1}{cos^2theta}- cos^2thetaright)=ldots$$
– gimusi
Nov 23 at 7:27
add a comment |
Hey thanks! but why did you times $frac {cos^2theta}{cos^2theta}$ to the equation, how does it works and can you do that? Also can i apply your technique in all cases?
– Tfue
Nov 23 at 7:23
2
@Tfue We can do that since it is equal to 1 and for the definition of the expression we are assuming $cos theta neq 0$.
– gimusi
Nov 23 at 7:24
1
You can divide/multiply both the numerator and denominator by $cos theta$ to rewrite the expression in a form that can be simplified more easily. (Essentially, you're multiplying/dividing by $1$, so it is equivalent to the original expression.)
– KM101
Nov 23 at 7:25
1
@Tfue Of course we can proceed in many others equivalent ways, for example $$frac {frac {1}{cos^2theta}- cos^2theta} {tan^2theta}=frac {frac {1}{cos^2theta}- cos^2theta} {frac{sin^2theta}{cos^2theta}}=frac{cos^2theta}{sin^2theta}left(frac {1}{cos^2theta}- cos^2thetaright)=ldots$$
– gimusi
Nov 23 at 7:27
Hey thanks! but why did you times $frac {cos^2theta}{cos^2theta}$ to the equation, how does it works and can you do that? Also can i apply your technique in all cases?
– Tfue
Nov 23 at 7:23
Hey thanks! but why did you times $frac {cos^2theta}{cos^2theta}$ to the equation, how does it works and can you do that? Also can i apply your technique in all cases?
– Tfue
Nov 23 at 7:23
2
2
@Tfue We can do that since it is equal to 1 and for the definition of the expression we are assuming $cos theta neq 0$.
– gimusi
Nov 23 at 7:24
@Tfue We can do that since it is equal to 1 and for the definition of the expression we are assuming $cos theta neq 0$.
– gimusi
Nov 23 at 7:24
1
1
You can divide/multiply both the numerator and denominator by $cos theta$ to rewrite the expression in a form that can be simplified more easily. (Essentially, you're multiplying/dividing by $1$, so it is equivalent to the original expression.)
– KM101
Nov 23 at 7:25
You can divide/multiply both the numerator and denominator by $cos theta$ to rewrite the expression in a form that can be simplified more easily. (Essentially, you're multiplying/dividing by $1$, so it is equivalent to the original expression.)
– KM101
Nov 23 at 7:25
1
1
@Tfue Of course we can proceed in many others equivalent ways, for example $$frac {frac {1}{cos^2theta}- cos^2theta} {tan^2theta}=frac {frac {1}{cos^2theta}- cos^2theta} {frac{sin^2theta}{cos^2theta}}=frac{cos^2theta}{sin^2theta}left(frac {1}{cos^2theta}- cos^2thetaright)=ldots$$
– gimusi
Nov 23 at 7:27
@Tfue Of course we can proceed in many others equivalent ways, for example $$frac {frac {1}{cos^2theta}- cos^2theta} {tan^2theta}=frac {frac {1}{cos^2theta}- cos^2theta} {frac{sin^2theta}{cos^2theta}}=frac{cos^2theta}{sin^2theta}left(frac {1}{cos^2theta}- cos^2thetaright)=ldots$$
– gimusi
Nov 23 at 7:27
add a comment |
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1
$$dfrac{1}{cos^2t}-cos^2t=dfrac{1-cos^4t}{cos^2t}=dfrac{(1-cos^2t)(1+cos^2t)}{cos^2t}=dfrac{(sin^2t)(1+cos^2t)}{cos^2t}=tan^2t(1+cos^2t)$$
– Nosrati
Nov 23 at 7:15
$dfrac{1/c^2-c^2}{s^2/c^2}=dfrac{1-c^4}{s^2}=1+c^2$
– Narasimham
Nov 24 at 15:38