sinx等于四分之三 cos2x等于多少?

2024-12-21 03:04:56
推荐回答(2个)
回答1:

sinx=3/4, cos2x=1-2[sinx]²=1-2[3/4]²=1-9/8=-1/8

回答2:

sinx= 3/4
cos2x= 1-2(sinx)^2 = 1- 3/2 = -1/2