## Trigonometry (10th Edition)

1. Internal angles of a triangle have a sum of 180° (x+20)+(210-3x)+(x)= 180 2. Solve the equation for x x-3x+x=180-210-20 -x=-50 x=50$^{\circ}$ 3. Then find other two angles by replacing x=50 (50)+20= 70$^{\circ}$ 210-3(50)=60$^{\circ}$