Definite Integration Question 27

Question: $ \int_0^{\pi /4}{{{\tan }^{2}}xdx=} $

[Roorkee 1983, Pb. CET 2000]

Options:

A) $ 1-\frac{\pi }{4} $

B) $ 1+\frac{\pi }{4} $

C) $ \frac{\pi }{4}-1 $

D) $ \frac{\pi }{4} $

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Answer:

Correct Answer: A

Solution:

$ \int_0^{\pi /4}{{{\tan }^{2}}xdx=\int_0^{\pi /4}{({{\sec }^{2}}x-1)dx}} $

$ =\int_0^{\pi /4}{{{\sec }^{2}}xdx-\int_0^{\pi /4}{1dx}} $ = $ [\tan x]_0^{\pi /4}-[x]_0^{\pi /4}=1-\frac{\pi }{4} $ .