Applications-Of-Derivatives Question 448

Question: The equation of the normal to the curve $ y=\sin \frac{\pi x}{2} $ at (1, 1) is

[AMU 1999]

Options:

A) $ y=1 $

B) $ x=1 $

C) $ y=x $

D) $ y-1=\frac{-2}{\pi }(x-1) $

Show Answer

Answer:

Correct Answer: B

Solution:

$ y=\sin \frac{\pi x}{2} $
Þ $ \frac{dy}{dx}=\frac{\pi }{2}\cos \frac{\pi }{2}x $ Þ $ {{( \frac{dy}{dx} )}_{(1,1)}}=0 $ \ Equation of normal is $ y-1=\frac{1}{0}(x-1) $
Þ $ x=1 $ .