145. 0,m≠n sinmxsinnxdx= 元,m=n (0,m≠n 146.sin msindcocx ,m=n 147.sin"dcos"xdx 1n=n-1.n-3 ..42 (n为大于1的正奇数),I,=1 n n-2 53 -1.”-3.…3(n为正偶数),1= 1n= n n-2 …422145. sin sin d mx nx x = 0, , m n m n 146. 0 sin sin d mx nx x = 0 cos cos d mx nx x = 0, , 2 m n m n 147. n I = 2 0 sin d n x x = 2 0 cos d n x x n I = 2 1 n n I n 1 3 4 2 2 5 3 n n n I n n ( n 为大于 1 的正奇数), 1 I =1 1 3 3 1 2 4 2 2 n n n I n n ( n 为正偶数), 0 I = 2