设∠c为x°2x+2x+x=180 x=36 故∠c=36° ∠b=∠a=2∠c=36°x2=72°
∠A=2∠C,∠B=2∠C,∠A+∠B+∠C=2∠C+2∠C+∠C=5∠C=180∠C=36∠A=72∠B=72
A=2CB=2CA+B+C=1805C=180C=36A=B=72
A＝B＝45º,C＝90º
