Q.

If ∫(1-5cos2xsin5x cos2x)dx=f(x)+C, where C is the constant of integration, then f(π6)-f(π4) is equal to   [2026]

1 43(8-6)  
2 23(4+6)  
3 13(26+3)  
4 13(26-3)  

Ans.

(1)

∫dxsin5xcos2x-5∫dxsin5x

=∫sec2x dxsin5x-5∫dxsin5x

By IBP

=tanxsin5x-∫5sin6xcosxtanx dx-5∫dxsin5x

=tanxsin5x+C

f(x)=tanxsin5x

f(π6)-f(π4)=253-(2)5=42-323

=323-42

=43(8-6)