Question

sin² 42° - sin² 12°=
​

Answer 1

Answer:

= (sin42+sin12)(sin42-sin12)

2sin((42+12)/2)cos((42-12)/2* 2 cos((42+12)/2)sin((42-12)/2

= 2sin27cos15*2cos27sin15

= 2sin27cos27*2sin15cos15

=sin(27*2)*sin(15*2)

= sin54*sin30

= (1/2)sin54°