# Ex 7.11, 21 - Chapter 7 Class 12 Integrals

Last updated at Dec. 8, 2016 by Teachoo

Last updated at Dec. 8, 2016 by Teachoo

Transcript

Ex 7.11, 21 Choose the correct answer : The value of 0 𝜋2𝑙𝑜𝑔 4 + 3 sin𝑥4+3 cos𝑥𝑑𝑥 is • 2 (B) 34 (C) 0 (D) −2 Let I= 0 𝜋2𝑙𝑜𝑔 4 + 3 sin𝑥4 + 3 𝑐𝑜𝑠 𝑥𝑑𝑥 ∴ I = 0 𝜋2𝑙𝑜𝑔 4 + 3𝑠𝑖𝑛 𝜋2 − 𝑥4 + 3𝑐𝑜𝑠 𝜋2 − 𝑥𝑑𝑥 I = 0 𝜋2𝑙𝑜𝑔 4 + 𝑐𝑜𝑠𝑥4 + 3 sin𝑥𝑑𝑥 Adding (1) and (2) i.e. (1) + (2) I +I= 0 𝜋2𝑙𝑜𝑔 4 + 3 sin𝑥4 + 3 cos𝑥𝑑𝑥+ 0 𝜋2𝑙𝑜𝑔 4 + 3 cos𝑥4 + 3 sin𝑥𝑑𝑥 2I = 0 𝜋2 𝑙𝑜𝑔 4 + 3 sin𝑥4 + 3 cos𝑥+𝑙𝑜𝑔 4 + 3 cos𝑥4 + 3 sin𝑥𝑑𝑥 2I = 0 𝜋2𝑙𝑜𝑔 4 + 3 sin𝑥4 + 3 cos𝑥× 4 + 3 cos𝑥4 + 3 sin𝑥𝑑𝑥 2I= 0 𝜋2𝑙𝑜𝑔 1𝑑𝑥 2I = 0 ∴ I = 0 ∴ Option C is correct.

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