Hello all.

I have a problem : Proof that triangle has an 60^{0}angle if and only if $\displaystyle sin3\alpha+sin3\beta+sin3\gamma=0$

Please help, no idea :(

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- Jan 26th 2013, 06:30 AMdarenceTriangle with angle of 60 degrees
Hello all.

I have a problem : Proof that triangle has an 60^{0}angle if and only if $\displaystyle sin3\alpha+sin3\beta+sin3\gamma=0$

Please help, no idea :( - Jan 26th 2013, 06:00 PMchiroRe: 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. - Jan 28th 2013, 03:07 AMdarenceRe: Triangle with angle of 60 degrees
Give me explanation. I dont understand :(

- Jan 28th 2013, 05:46 PMchiroRe: 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.