Question

【三角恒等变换】cos(33°-x)sin(63°-x)-cos(x+57°)sin(27°+x)

Answer 1

cos(33°-x)sin(63°-x)-cos(x+57°)sin(27°+x)

=cos[90°-(x+57°)]sin[90°-(x+27°]-cos(x+57°)sin(x+27°)

=sin(x+57°)cos(x+27°)-cos(x+57°)sin(x+27°)

=sin[(x+57°)-(x+27°)]

=sin30°

=1/2