cosx-1/2(cosxcosπ/3+sinxsinπ/3)如何得到-根号3除以2(sinxcosπ/3-cosxsinπ/3)_数学解答

cosx-1/2(cosxcosπ/3+sinxsinπ/3)如何得到-根号3除以2(sinxcosπ/3-cosxsinπ/3)?

人气：334 ℃　时间：2020-06-13 11:41:50

解答

原式=cosx-1/2(cosx(1/2)+sinx(√3/2))
=3/4cosx-√3/4sinx
=-√3/2(1/2sinx-√3/2cosx )
=-√3/2(sinxcosπ/3-cosxsinπ/3)