One angle of triangle

**Stuck Man** · January 25th 2010, 06:22 AM

I'm not sure what formula is needed to answer the attached question. Maybe the half angle formulae?

**Grandad** · January 25th 2010, 06:35 AM

Hello Stuck Man

Originally Posted by Stuck Man

I'm not sure what formula is needed to answer the attached question. Maybe the half angle formulae?

$\sin A = \sin(\pi-A)$

$=\sin(B+C)$

$=\sin B\cos C + \cos B \sin C$

Can you see it OK from here?

Grandad

**Sudharaka** · January 25th 2010, 06:38 AM

Grandad had answered the question by the time I written my reply. So I removed it.

**HallsofIvy** · January 25th 2010, 06:56 AM

Dontcha just hate when he does that!

**Stuck Man** · January 25th 2010, 06:58 AM

I found the solution by solving sin C and cos C. Thanks.

Thread: One angle of triangle