Definite Integration Question 384

Question: The ratio of the areas bounded by the curves $ y=\cos x $ and $ y=\cos 2x $ between $ x=0, $

$ x=\pi /3 $ and $ x- $ axis, is

[MP PET 1997]

Options:

A) $ \sqrt{2}:1 $

B) $ 1:1 $

C) $ 1:2 $

D) $ 2:1 $

Show Answer

Answer:

Correct Answer: D

Solution:

$ A_1=\int_0^{\pi /3}{\cos xdx=\frac{\sqrt{3}}{2}} $ , $ A_2=\int_0^{\pi /3}{\cos 2xdx=\frac{\sqrt{3}}{4}} $

$ A_1:A_2=2:1 $ .