Question

sin(75+a)sin(75-a)-cos(15+a)cos(15-a)=0
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Answer 1

Answer:

Step-by-step explanation:

sin(75+a)sin(75-a)-cos(15+a)cos(15-a)

We know that Cos(90-θ) = Sinθ.

=> Sin(75+a)SIn(75-a) - Cos(90 - (75 - a)) .Cos(90 - (75+a))  

=> Sin(75+a)SIn(75-a) - Sin(75 - a)Sin(75+a)

= 0.

Hence proved.