Question

几个三角函数积分,实在算不明白了,

Answer 1

1.sinx cosy = 1/2 [(sin(x+y) + sin(x-y)]

= 1/2 [sin(theta-pi/2p + nptheta) + sin(theta-pi/2p - nptheta)]

= 1/2 [sin[(np+1)theta - pi/2p] + sin[(1-np)theta - pi/2p]]

积分 = 1/(2(np+1)) cos[(np+1) theta - pi/2p] - 1/(2(1-np))cos..