Prove that: (cos α+cos β)2+(sin α+sin β)2=4 cos2 (α−β2) – InterviewSolution

1.

Prove that: (cos α+cos β)2+(sin α+sin β)2=4 cos2 (α−β2)

Answer»

Prove that:

${(c o s α + c o s β)}^{2} + {(s i n α + s i n β)}^{2} = 4 c o s^{2} (\frac{α - β}{2})$

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