Differentiation Question 419
Question: If $ x=a(\cos \theta +\theta \sin \theta ) $ , $ y=a(\sin \theta -\theta \cos \theta ), $ then $ \frac{dy}{dx}= $
[DCE 1999]
Options:
A) $ \cos \theta $
B) $ \tan \theta $
C) $ \sec \theta $
D) cosecq
Show Answer
Answer:
Correct Answer: B
Solution:
$ \frac{dy}{dx}=\frac{dy/d\theta }{dx/d\theta } $ = $ \frac{a[\cos \theta -\theta (-\sin \theta )-\cos \theta ]}{a[-\sin \theta +\theta \cos \theta +\sin \theta ]} $
= $ \frac{\theta \sin \theta }{\theta \cos \theta }=\tan \theta $ .
BETA
