Find the value of 2.arccos 3/√13 + arccot 16/63 + arccos 7/25

Answer: arctan 3/4

How to solve this?

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- September 24th 2008, 08:21 AMfardeen_genFind the arccos value?
Find the value of 2.arccos 3/√13 + arccot 16/63 + arccos 7/25

Answer: arctan 3/4

How to solve this? - September 25th 2008, 06:02 AMfardeen_gen
I was told that assuming an inverse trigonometric function as an angle simplifies the problem. This doesn't seem to help me in this problem.

- September 25th 2008, 01:04 PMMoo
Hello,

I've seen some problems solved this way, but I just can't do them...

I'll try, but MY way, that is to say : calculations ! (Rofl)

Here are the formula I'll use :

(formula 18 : Inverse Tangent -- from Wolfram MathWorld)

(formula 12 : Inverse Cosine -- from Wolfram MathWorld)

(formula 36 : Inverse Tangent -- from Wolfram MathWorld)

Using formula (1), we have to solve :

Using formula (2) and after some simplifications, we have to solve :

Using formula (3), we get :

Using formula (3) once again, we get :

And I must say I'm lost here... :(