cos theta plus cos 120 degree plus theta plus cos 120 degree minus theta
Answers
Answered by
2
Answer:
Cos A + cos(120° + A) + cos(120 - A)
= Cos A + 2 cos{( 120°+A+120°-A)/2}cos{120°+A-120+A)/2 ………(1) by using the formula
Cos C + cos D = 2 cos (C+D)/2 cos (C-D)/2
(1) reduces to Cos A + 2 cos 120° cos A
= Cos A + 2 (-1/2) cos A
= 0
Similar questions