Please help, Contest questions...

[MathExpert]

1) What kind of triangle is ABC if for his angles we have:
sin[2*(alfa)]=2sin[beta]*cos[gama]

2) If acos[alfa] + bsin[alfa]=acos[beta]+b[sin[beta] , prove that sin(alfa+beta)=2ab/(a^2+b^2)

[dextercioby]

For question #1,are u sure that equilateral triangle is the only possibble sollution...?

Daniel.

[dextercioby]

I wanted to tell u that the "HINT" for the second problem would have led nowhere...

Daniel.