4sinx+4sin(2派/3-x)
1个回答

原式=4sinx+4sin【π-(2π/3-x)】

=4sinx+4sin(x+π/3)(拆开)

=4sinx+4(sinxcosπ/3+cosxsinπ/3)

=4sinx+4(1/2sinx+√3/2cosx)

=4sinx+2sinx+2√3cosx

=6sinx+2√3cosx

=4√3(√3/2sinx+1/2cosx)

=4√3(sinxcosπ/6+cosxsinπ/6)

=4√3sinx(x+π/6)

O啦~