Question

y=sin(2x+30°)-cos(2x+60°)的最小正周期和最大值

A 兀 1 B兀 1.732 C 2兀 D2兀 1.732

Answer 1

y=sin(2x+30°)-cos(2x+60°)
=sin2xcos30+sin30cos2x-(cos2xcos60-sin2xsin60)
=√3sin2x/2+cos2x/2-cos2x/2+sin2x√3/2
=√3sin2x
T=2兀/2=兀
最大值√3=1.732
B

追问

谢谢啦！不过，过程可不可以再写的详细点，我比较笨。由sin2xcos30+sin30cos2x-(cos2xcos60-sin2xsin60)到√3sin2x/2+cos2x/2-cos2x/2+sin2x√3/2
这一步是怎么变得

Answer 2

B