How do you write as a single expression #cos(2a) cos(a) - sin(2a) sin(a)# using the double angle identity?
1 Answer
Aug 31, 2015
Simplify trig expression
Ans: cos (3a)
Explanation:
cos (2a).cos (a) - sin (2a).sin (a) = cos (2a + a) = cos 3a
