# Triangle with angle of 60 degrees

• January 26th 2013, 06:30 AM
darence
Triangle with angle of 60 degrees
Hello all.
I have a problem : Proof that triangle has an 600 angle if and only if $sin3\alpha+sin3\beta+sin3\gamma=0$
• January 26th 2013, 06:00 PM
chiro
Re: Triangle with angle of 60 degrees
Hey darence.

First off, we know that all angles equal 180 degrees or pi radians.

Now y = pi - b - pi/3 so prove that sin(3*pi/3) + sin(3*b) + sin(3*(2pi/3 - b) = 0 and you're done.
• January 28th 2013, 03:07 AM
darence
Re: Triangle with angle of 60 degrees
Give me explanation. I dont understand :(
• January 28th 2013, 05:46 PM
chiro
Re: Triangle with angle of 60 degrees
Basically I set one angle to 60 degrees (or pi/3 radians) and the rest add up 180 degrees (or pi radians).

Then you just show that the equation holds and then you're done.