Упростите: cos(a-2b)-cos(a+2b)

Question

Упростите: cos(a-2b)-cos(a+2b)

Answer 1

соs(a-2b)-cos(a+2b)=

(2sin((a-2b)+(a+2b))/2)(sin((a+2b)-(a-2b))/2)=

2sin(2a/2)sin(4b/2)=

2sinasin2b