Question

10.
Assertion (A): cos^3 x + cos^3 (120° + x)+cos^3 (120° - x) = 3/4cos 3x
Reason (R) : cosx + cos(120° +x)+cos(120° - x)= 0 and
co
cos x.cos(120° +x ).cos(120° - x) =1/4 cos 3x.

a) A is true, R is true and R is correct explanation of A.
b) A is true, R is true and R is not correct explanation of A.
c) A is true, R is is false
d) A is false, R is true​

Answer 1

Answer:

(a),is the right answer..