NTA Abhyas JEE Main2020MathematicsDefinite IntegrationPractice
Let a n = ∫ 0 π 2 1 - cos 2 n x 1 - cos 2 x d x , then a 1 , a 2 , a 3 , . . . . . . are in
Options
- AArithmetic Progression
- BGeometric Progression
- CHarmonic Progression
- DArithmetic Geometric Progression
Correct answer
A. Arithmetic Progression
Step-by-step solution
a n + 2 + a n - 2 a n + 1 = ∫ 0 π 2 1 - cos ⁡ 2 n + 2 x 1 - cos ⁡ 2 x d x + ∫ 0 π 2 1 - cos ⁡ 2 n x 1 - cos ⁡ 2 x d x - 2 ∫ 0 π 2 1 - cos ⁡ 2 n + 1 x 1 - cos ⁡ 2 x d x = ∫ 0 π / 2 1 - cos ⁡ 2 n + 4 x + 1 - cos ⁡ 2 n x - 2 + 2 cos ⁡ 2 n + 2 x 1 - cos ⁡ 2 x d x = ∫ 0 π 2 2 cos ⁡ 2 n + 2 x - cos ⁡ 2 n + 4 x + cos ⁡ 2 n x 1 - cos ⁡ 2 x d x = ∫ 0 π 2 2 cos ⁡ 2 n + 2