Show that angle A is less than 60 degrees if a < (b+c)/2

[Canada_Whiz]

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

 

[mathman]

Have you tried the law of cosines?

a²=b²+c²-2bccosA