Question

hello guys solve this question.

Answer 1

Cos 3A = 4Cos cube A - 3 Cos A
Cos 3 X 30 = 4 Cos cube 30 - 3 Cos 30
Cos 90 = 4 (√3/2) cube - 3(√3/2)
0 = 4 ( 3√3/ 8 ) - 3√3/2
0 = 3√3/2 - 3√3/2
0=0
Hence Proved

Please Mark As the Brainliest