Applications Of Derivatives Question 148

Question: The angle of intersection of curves $ y=x^{2}, $ $ 6y=7-x^{3} $ at (1, 1) is

[Kurukshetra CEE 2002]

Options:

A) $ \pi /4 $

B) $ \pi /3 $

C) $ \pi /2 $

D) $ \pi $

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Answer:

Correct Answer: C

Solution:

$ y=x^{2} $

therefore $ {{( \frac{dy}{dx} )} _{(1,,1)}}=m_1=2x=2 $

$ 6y=7-x^{3}\Rightarrow 6,.,\frac{dy}{dx}=-3x^{2} $

therefore $ {{( \frac{dy}{dx} )} _{(1,,1)}}=m_2=-\frac{1}{2} $

Clearly $ m_1m_2=-1, $ therefore angle of intersection is $ \frac{\pi }{2} $ .