Quantitative Aptitude Ques 977
Question: The value of $ \frac{1}{cosec\theta -cot\theta }-\frac{1}{\sin \theta }, $ is
Options:
A) $ \cot \theta $
B) $ cosec\theta $
C) $ \tan \theta $
D) $ 1 $
Show Answer
Answer:
Correct Answer: A
Solution:
- $ \frac{1}{cosec\theta -cot\theta }-\frac{1}{\sin \theta } $
$ =\frac{1}{\frac{1}{\sin \theta }-\frac{\cos \theta }{\sin \theta }}-\frac{1}{\sin \theta }=\frac{\sin \theta }{1-\cos \theta }-\frac{1}{\sin \theta } $
$ =\frac{{{\sin }^{2}}\theta -(1-\cos \theta )}{(1-\cos \theta )\sin \theta } $
$ =\frac{1-{{\cos }^{2}}\theta -1+\cos \theta }{(1-\cos \theta )\sin \theta } $ $ [\because {{\sin }^{2}}\theta +{{\cos }^{2}}\theta =1] $
$ =\frac{\cos \theta (1-\cos \theta )}{(1-\cos \theta )\sin \theta }=\frac{\cos \theta }{\sin \theta }=\cot \theta $