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Nahin

Guest

Trigonometry

Prove that sin-1(3/5)+sin-1(5/13)=cos-1(33/65)
Please help me solve this
With a detailed explanation
I hope u help me do it

Bob

Administrator

Registered: 2010-06-20

Posts: 10,640

Re: Trigonometry

Hi Nahin,

Welcome to the forum.

These three entities are angles so all the trig formulas can be applied.

Eg work out 13^2 - 5^2 and square root it and you  have the cosine of the angle whose sine is 5/13.

And you can use the compound angle formula to write the cosine of the LHS as an expression involving sines and cosines of the angles eg.cos sin-1(3/5) = 4/5

That should enable you to show that LHS =RHS

Bob

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