1.

Prove cos A + cos(120-A) + cos(120+A) = 0

Answer»

Hay!!



Dear user -



PROVE THAT COSA + COS(120-A)+COS(120+A)=0



❄here is ur answer ❄


LHS=>


CosA+Cos(120-A) + Cos(120+A)



\frac{cosa + 2cos(120 - a + 120 + a)}{2cos(120 - a - 120 - a)}

we know that formula


( cos C+ cosD = 2cos (C+D)/2.cos (C-D) /2)


=> cosA+2cos120 cos-A


=> cosA+2cos (180-60) cosA


=> cosA+2(-cos60) cosA


cosa - 2 \times  \frac{1}{2}cosa

=> cosA-cosA


=> 0

Hence PROVED


I hope it's HELP you






Discussion

No Comment Found

Related InterviewSolutions