Posted by **Ansley** on Sunday, February 26, 2012 at 8:29pm.

sin [sin -1 (7/25) - cos -1 (-8/17)]

- trig -
**Reiny**, Sunday, February 26, 2012 at 8:48pm
let A = sin^-1 (7/25)

then cosA = 24/25 ---> sinA = 7/25

let B = cos^-1 (-8/17)

cosB = --8/17 , let's assume B is in II

sin B = 15/17

so sin [sin -1 (7/25) - cos -1 (-8/17)]

= sin (A - B)

= sinAcosB - cosAsinB

= (7/25)(-8/17) - (24/25)(15/17)

= (-56 - 360)/425

**= -416/425**

check with calculator:

A = 16.26°

B = 118.07°

A-B = -101.81°

sin(-101.81°) = -.9788

-416/425 = -.9788 , how about that?

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