this is true?

Question

http://www.uppic.com/uploads/14201039571.jpg

can i solve this way?

Answer 1

No, you can't: 3sin(x-a) isn't identical to sin3(x-a), although it is true for the special case of x=a, and it's also true when x=a+(pi)n, where n is an integer (positive or negative) and x and a are measured in radians. If they're in degrees, it's x=a+180n.

sin(3x-3a)=sin3xcos3a-cos3xsin3a is a trig identity which is true for all values of x and a.