Mathematics

Problem

A, B

and

C

are the angles of a triangle, show that

$\sin 2A$	$\sin C$	$\sin B$
$\sin C$	$\sin 2B$	$\sin A$
$\sin B$	$\sin A$	$\sin 2C$

= 0.

$-1 + \cos B$	$\cos C + \cos B$	$\cos B$
$\cos C + \cos A$	$-1 + \cos A$	$\cos A$
$-1 + \cos B$	$-1 + \cos A$	$-1$

= 0.