How to simplify $ \dfrac{{\csc \left( { - x} \right)}}{{\cot \left( { - x} \right)}} $ ?
Answer
622.8k+ views
Hint: csc stands for cosec. $ \cos ec\left( x \right) $ is a trigonometric function and is reciprocal of $ \sin \left( x \right) $ . $ \cos ec\left( x \right) $ can be defined as the ratio between hypotenuse and perpendicular to theta ( $ \theta $ ). $ \cot \left( x \right) $ is also a trigonometric function and is reciprocal to $ \tan \left( x \right) $ . $ \cot \left( x \right) $ can be defined as the ratio between base and perpendicular to theta ( $ \theta $ ). Both of these trigonometric functions are odd functions.
Complete step-by-step answer:
As we already know that both $ \cos ec\left( x \right) $ and $ \cot \left( x \right) $ are odd functions, which means that $ f\left( { - x} \right) = - f\left( x \right) $ . So, we can say that,
$ \Rightarrow \csc \left( { - x} \right) = - \csc \left( x \right) $ ---(1)
$ \Rightarrow \cot \left( { - x} \right) = - \cot \left( x \right) $ ---(2)
We are given that $ \dfrac{{\csc \left( { - x} \right)}}{{\cot \left( { - x} \right)}} $ ,
Using equation (1) and (2) in given question we get,
$ \Rightarrow \dfrac{{\csc \left( x \right)}}{{\cot \left( x \right)}} $ ---(3)
We know that $ \cos ec\left( x \right) $ is reciprocal of $ \sin \left( x \right) $ which means
$ \Rightarrow \csc \left( x \right) = \dfrac{1}{{\sin \left( x \right)}} $ ---(4)
And $ \cot \left( x \right) $ is the reciprocal of $ \tan \left( x \right) $ which means
$ \Rightarrow \cot \left( x \right) = \dfrac{{\cos \left( x \right)}}{{\sin \left( x \right)}} $ ---(5)
Now, substituting the values of equation (4) and (5) in equation (3), we get,
$
\Rightarrow \dfrac{{\dfrac{1}{{\sin \left( x \right)}}}}{{\dfrac{{\cos \left( x \right)}}{{\sin \left( x \right)}}}} \\
\Rightarrow \dfrac{1}{{\sin \left( x \right)}} \times \dfrac{{\sin \left( x \right)}}{{\cos \left( x \right)}} \;
$
$ \sin \left( x \right) $ cuts and cancels off and we get,
$ \Rightarrow \dfrac{1}{{\cos \left( x \right)}} $ ---(6)
We know that, $ \sec \left( x \right) $ is the reciprocal of $ \cos \left( x \right) $ which means that, $ \sec \left( x \right) = \dfrac{1}{{\cos \left( x \right)}} $ . Substituting the same in equation (6) and we get,
$ \Rightarrow \sec \left( x \right) $
Thus, $ \dfrac{{\csc \left( { - x} \right)}}{{\cot \left( { - x} \right)}} = \sec \left( x \right) $ .
So, the correct answer is “Sec x”.
Note: Before solving any trigonometric question, students should keep all the necessary trigonometric identities in their mind. This will help them to solve any question easily. Students should also remember that $ \cos ec\left( x \right) $ is not the inverse of $ \sin \left( x \right) $ and cannot be written as $ {\sin ^{ - 1}}x $ . The same applies to $ \sec \left( x \right) $ as well as $ \cot \left( x \right) $ . Students should keep in mind that $ \sec \left( x \right) $ is the reciprocal of $ \cos \left( x \right) $ , $ \cos ec\left( x \right) $ is the reciprocal of $ \sin \left( x \right) $ and $ \cot \left( x \right) $ is the reciprocal of $ \tan \left( x \right) $ . In addition to $ \cos ec\left( x \right) $ and $ \cot \le
Complete step-by-step answer:
As we already know that both $ \cos ec\left( x \right) $ and $ \cot \left( x \right) $ are odd functions, which means that $ f\left( { - x} \right) = - f\left( x \right) $ . So, we can say that,
$ \Rightarrow \csc \left( { - x} \right) = - \csc \left( x \right) $ ---(1)
$ \Rightarrow \cot \left( { - x} \right) = - \cot \left( x \right) $ ---(2)
We are given that $ \dfrac{{\csc \left( { - x} \right)}}{{\cot \left( { - x} \right)}} $ ,
Using equation (1) and (2) in given question we get,
$ \Rightarrow \dfrac{{\csc \left( x \right)}}{{\cot \left( x \right)}} $ ---(3)
We know that $ \cos ec\left( x \right) $ is reciprocal of $ \sin \left( x \right) $ which means
$ \Rightarrow \csc \left( x \right) = \dfrac{1}{{\sin \left( x \right)}} $ ---(4)
And $ \cot \left( x \right) $ is the reciprocal of $ \tan \left( x \right) $ which means
$ \Rightarrow \cot \left( x \right) = \dfrac{{\cos \left( x \right)}}{{\sin \left( x \right)}} $ ---(5)
Now, substituting the values of equation (4) and (5) in equation (3), we get,
$
\Rightarrow \dfrac{{\dfrac{1}{{\sin \left( x \right)}}}}{{\dfrac{{\cos \left( x \right)}}{{\sin \left( x \right)}}}} \\
\Rightarrow \dfrac{1}{{\sin \left( x \right)}} \times \dfrac{{\sin \left( x \right)}}{{\cos \left( x \right)}} \;
$
$ \sin \left( x \right) $ cuts and cancels off and we get,
$ \Rightarrow \dfrac{1}{{\cos \left( x \right)}} $ ---(6)
We know that, $ \sec \left( x \right) $ is the reciprocal of $ \cos \left( x \right) $ which means that, $ \sec \left( x \right) = \dfrac{1}{{\cos \left( x \right)}} $ . Substituting the same in equation (6) and we get,
$ \Rightarrow \sec \left( x \right) $
Thus, $ \dfrac{{\csc \left( { - x} \right)}}{{\cot \left( { - x} \right)}} = \sec \left( x \right) $ .
So, the correct answer is “Sec x”.
Note: Before solving any trigonometric question, students should keep all the necessary trigonometric identities in their mind. This will help them to solve any question easily. Students should also remember that $ \cos ec\left( x \right) $ is not the inverse of $ \sin \left( x \right) $ and cannot be written as $ {\sin ^{ - 1}}x $ . The same applies to $ \sec \left( x \right) $ as well as $ \cot \left( x \right) $ . Students should keep in mind that $ \sec \left( x \right) $ is the reciprocal of $ \cos \left( x \right) $ , $ \cos ec\left( x \right) $ is the reciprocal of $ \sin \left( x \right) $ and $ \cot \left( x \right) $ is the reciprocal of $ \tan \left( x \right) $ . In addition to $ \cos ec\left( x \right) $ and $ \cot \le
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

