题目

几道辅助角公式题~
sinx+cosx=?
sinx-cosx=?
sinx+根号3*cosx=?
sinx-根号3*cosx=?
根号3*sinx+cosx=?
根号3*sinx-cosx=?

提问时间：2021-01-02

答案

sinx+cosx
=√2(sinxcosπ/4+cosxsinπ/4)
=√2sin(x+π/4)
sinx-cosx
=√2(sinxcosπ/4-cosxsinπ/4)
=√2sin(x-π/4)
sinx+根号3*cosx
=2(sinxcosπ/3+cosxsinπ/3)
=2sin(x+π/3)
sinx-根号3*cosx
=2(sinxcosπ/3-cosxsinπ/3)
=2sin(x-π/3)
根号3*sinx+cosx
=2(sinxcosπ/6+cosxsinπ/6)
=2sin(x+π/6)
根号3*sinx-cosx
=2(sinxcosπ/6-cosxsinπ/6)
=2sin(x-π/6)