The problem is

Determine the exact value of

sin (2 arccos (8/17))

The triangle for sin (arccos x) = sqroot(1-x^2). I have no idea how the answer is (240/289).

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- December 7th 2007, 07:41 PMshogunhdInverse Trig
The problem is

Determine the exact value of

sin (2 arccos (8/17))

The triangle for sin (arccos x) = sqroot(1-x^2). I have no idea how the answer is (240/289). - December 7th 2007, 08:00 PMSoroban
Hello, shogunhd!

Quote:

Determine the exact value of: .

Let

So, is in a right triangle with: .

. . Using Pythagorus, we find that: .

Hence: .

The problem becomes: .

- December 8th 2007, 04:24 AMKrizalid
Similar to this problem.

Since

Plug and you're done.