99 Percentile Qs Bank for JEE MainMathematicsDefinite Integration
If ∫ 0 π log ( sin x ) d x = 8 k , then ∫ 0 π / 4 log ( 1 + tan x ) d x =
Options
- Ak
- B- k
- Ck 2
- D4   k
Correct answer
B. - k
Step-by-step solution
Let I = ∫ 0 π / 4 log ( 1 + tan x ) d x Using property of integration ∫ 0 a f ( x ) d x = ∫ 0 a f ( a - x ) d x ⇒ I = ∫ 0 π 4 log 1 + tan π 4 - x d x ⇒ I = ∫ 0 π 4 log 2 1 + tan x d x ⇒ I = ∫ 0 π 4 log 2 d x - ∫ 0 π 4 log 1 + tan x d x ⇒ I = π 4 log 2 - I               ∵ I = ∫ 0 π 4 log 1 + tan x d x ⇒ 2 I = π 4 log 2 ⇒ I = π 8 log 2   &#