sinx-cosx等于?

问题描述:

sinx-cosx等于?
sinx-cosx怎样化成同角?

sinx-cosx
=√2(√2/2*sinx-√2/2cosx)
=√2(sinxcosπ/4-cosxsinπ/4)
=√2sin(x-π/4)我想问下sinx+cosx=√2sin(x+π/4) ? 只是中间的符号改变而已?对的