Y=Asin(-2x-π/6)的初相是什么?答案是-5π/6还是7π/6?请解释下为什么~

Question

Y=Asin(-2x-π/6)的初相是什么?
答案是-5π/6还是7π/6?请解释下为什么~

Answer 1

如果A>0
则y=-Asin(2x+π/6)
=Asin(π+2x+π/6)
=Asin(2x+7π/6)
所以初相是7π/6