# Trignometry Proof Help

1. Apr 8, 2010

Trignometry Proof Help!!!

If a,b,c are sides in a triangle such that a<1/2(b+c) show that angle A (the angle opposite to side a) is less than 60 degrees

Last edited: Apr 8, 2010
2. Apr 8, 2010

### mathman

Re: Trignometry Proof Help!!!

Have you tried the law of cosines?

a2=b2+c2-2bccosA