函数y=sinx-cosx化为正弦函数为?

题目

函数y=sinx-cosx化为正弦函数为?

答案

y=sinx-cosx
=√2*(√2/2*sinx-√2/2*cosx)
=√2(sinxcosπ/4-cosxsinπ/4)
=√2sin(x-π/4) .