What is ${\cot ^2}\theta $. in terms of non- exponential trigonometric function?
Answer
539.7k+ views
Hint: In this question, we are given a trigonometric function ${\cot ^2}\theta $. And we have to convert it in non-exponential trigonometric function i.e., we have to make its degree one.
For that, we will first write $\cot \theta $ in the form of $\sin \theta $ and $\cos \theta $ .
Then, we will use the half-angle formulas for removing their exponential powers.
Formulae to be used:
$\cot \theta = \dfrac{{\cos \theta }}{{\sin \theta }}$ ,
$\cos 2\theta = 1 - 2{\sin ^2}\theta $ ,
$\cos 2\theta = 2{\cos ^2}\theta - 1$ .
Complete answer:
Given trigonometric function is ${\cot ^2}\theta $ .
To write the given trigonometric function in terms of the non-exponential function.
For that, first, we will write $\cot \theta $ in the form of $\sin \theta $ and $\cos \theta $ , i.e., we can write it as \[{\cot ^2}\theta = \dfrac{{{{\cos }^2}\theta }}{{{{\sin }^2}\theta }}\] .
Now, we know that, $\cos 2\theta = 1 - 2{\sin ^2}\theta $ , so, adding $2{\sin ^2}\theta $ on both sides, we get, $\cos 2\theta + 2{\sin ^2}\theta = 1 - 2{\sin ^2}\theta + 2{\sin ^2}\theta $ , i.e., $\cos 2\theta + 2{\sin ^2}\theta = 1$ . Now, subtracting $\cos 2\theta $ from both sides, we get, $\cos 2\theta + 2{\sin ^2}\theta - \cos 2\theta = 1 - \cos 2\theta $ , i.e., $2{\sin ^2}\theta = 1 - \cos 2\theta $ . Now, finally, divide both sides by $2$ , we get, \[{\sin ^2}\theta = \dfrac{{1 - \cos 2\theta }}{2}\] .
Similarly, we can also have $\cos 2\theta = 2{\cos ^2}\theta - 1$ , adding $1$ on both sides, we get, $\cos 2\theta + 1 = 2{\cos ^2}\theta - 1 + 1$ , i.e., $\cos 2\theta + 1 = 2{\cos ^2}\theta $ . Now, dividing, both sides by $2$ , we get, $\dfrac{{\cos 2\theta + 1}}{2} = \dfrac{{2{{\cos }^2}\theta }}{2}$ , which can also be written as ${\cos ^2}\theta = \dfrac{{1 + \cos 2\theta }}{2}$ .
Put these values in \[{\cot ^2}\theta = \dfrac{{{{\cos }^2}\theta }}{{{{\sin }^2}\theta }}\] , we get, \[{\cot ^2}\theta = \dfrac{{\dfrac{{1 + \cos 2\theta }}{2}}}{{\dfrac{{1 - \cos 2\theta }}{2}}}\] , i.e., \[{\cot ^2}\theta = \dfrac{{\left( {1 + \cos 2\theta } \right) \times 2}}{{\left( {1 - \cos 2\theta } \right) \times 2}}\] , now $2$ will be canceled out by $2$ , then we get, \[{\cot ^2}\theta = \dfrac{{1 + \cos 2\theta }}{{1 - \cos 2\theta }}\] .
Hence, the non-exponential trigonometric function of ${\cot ^2}\theta $ is \[\dfrac{{1 + \cos 2\theta }}{{1 - \cos 2\theta }}\] .
Note:
Non- exponential function simply means the resultant function should not have a degree of more than one, i.e., the highest power must be equal to one.
One must have knowledge of all the basic identities associated with the trigonometric functions.
These types of questions are a bit tricky and difficult, so one can do silly mistakes if not done with full concentration.
For that, we will first write $\cot \theta $ in the form of $\sin \theta $ and $\cos \theta $ .
Then, we will use the half-angle formulas for removing their exponential powers.
Formulae to be used:
$\cot \theta = \dfrac{{\cos \theta }}{{\sin \theta }}$ ,
$\cos 2\theta = 1 - 2{\sin ^2}\theta $ ,
$\cos 2\theta = 2{\cos ^2}\theta - 1$ .
Complete answer:
Given trigonometric function is ${\cot ^2}\theta $ .
To write the given trigonometric function in terms of the non-exponential function.
For that, first, we will write $\cot \theta $ in the form of $\sin \theta $ and $\cos \theta $ , i.e., we can write it as \[{\cot ^2}\theta = \dfrac{{{{\cos }^2}\theta }}{{{{\sin }^2}\theta }}\] .
Now, we know that, $\cos 2\theta = 1 - 2{\sin ^2}\theta $ , so, adding $2{\sin ^2}\theta $ on both sides, we get, $\cos 2\theta + 2{\sin ^2}\theta = 1 - 2{\sin ^2}\theta + 2{\sin ^2}\theta $ , i.e., $\cos 2\theta + 2{\sin ^2}\theta = 1$ . Now, subtracting $\cos 2\theta $ from both sides, we get, $\cos 2\theta + 2{\sin ^2}\theta - \cos 2\theta = 1 - \cos 2\theta $ , i.e., $2{\sin ^2}\theta = 1 - \cos 2\theta $ . Now, finally, divide both sides by $2$ , we get, \[{\sin ^2}\theta = \dfrac{{1 - \cos 2\theta }}{2}\] .
Similarly, we can also have $\cos 2\theta = 2{\cos ^2}\theta - 1$ , adding $1$ on both sides, we get, $\cos 2\theta + 1 = 2{\cos ^2}\theta - 1 + 1$ , i.e., $\cos 2\theta + 1 = 2{\cos ^2}\theta $ . Now, dividing, both sides by $2$ , we get, $\dfrac{{\cos 2\theta + 1}}{2} = \dfrac{{2{{\cos }^2}\theta }}{2}$ , which can also be written as ${\cos ^2}\theta = \dfrac{{1 + \cos 2\theta }}{2}$ .
Put these values in \[{\cot ^2}\theta = \dfrac{{{{\cos }^2}\theta }}{{{{\sin }^2}\theta }}\] , we get, \[{\cot ^2}\theta = \dfrac{{\dfrac{{1 + \cos 2\theta }}{2}}}{{\dfrac{{1 - \cos 2\theta }}{2}}}\] , i.e., \[{\cot ^2}\theta = \dfrac{{\left( {1 + \cos 2\theta } \right) \times 2}}{{\left( {1 - \cos 2\theta } \right) \times 2}}\] , now $2$ will be canceled out by $2$ , then we get, \[{\cot ^2}\theta = \dfrac{{1 + \cos 2\theta }}{{1 - \cos 2\theta }}\] .
Hence, the non-exponential trigonometric function of ${\cot ^2}\theta $ is \[\dfrac{{1 + \cos 2\theta }}{{1 - \cos 2\theta }}\] .
Note:
Non- exponential function simply means the resultant function should not have a degree of more than one, i.e., the highest power must be equal to one.
One must have knowledge of all the basic identities associated with the trigonometric functions.
These types of questions are a bit tricky and difficult, so one can do silly mistakes if not done with full concentration.
Recently Updated Pages
Write structures of the following compounds i 2 Chloro3methylpentane class 11 chemistry CBSE

What is BLO What is the full form of BLO class 8 social science CBSE

Explain the Treaty of Vienna of 1815 class 10 social science CBSE

A Paragraph on Pollution in about 100-150 Words

XIX+XXX A 49 B 51 C 55 D 44 class 5 maths CBSE

If x a + bt + ct2 where x is in meters and t is in class 11 physics CBSE

Trending doubts
One Metric ton is equal to kg A 10000 B 1000 C 100 class 11 physics CBSE

Find the value of the expression given below sin 30circ class 11 maths CBSE

What do you mean by retardation What is its SI uni class 11 physics CBSE

Draw a diagram of nephron and explain its structur class 11 biology CBSE

10 examples of friction in our daily life

Difference between physical and chemical change class 11 chemistry CBSE

