t*sin^3(t) dt.포인트 구하세요.

t*sin^3(t) dt.포인트 구하세요.

sin^3(t) = [1-cos(2t)] sint / 2 = (3/4) sint - (1/4) sin(3t)
I = (3/4) t d(-cost) + (1/12) t d(cos3t)
= (-3/4) [t cost - cost dt ] + (1/12) [t cos(3t) - cos(3t) dt ]
= (-3/4) [t cost - sint] + (1/12) [t cos(3t) - (1/3) sin(3t) ] + C