Question

The sum of two angles of a triangle is 80° and their is 20°.Find all the angles.

Answer 1

Let the angles be x, y and z then
x+y+z=180°
A/Q-
Case I: x+y=80°
               x=80°-y------------(1)
Case II: x-y=20°
              x=20°+y---------(2)
On comparing equation (1) and (2)
            80°-y=20°+y
             ⇒2y=80°-20°
                 y=60°/2
                 y=30°
         Then x=80°-30°
                 x=50°
We know that x+y+z=180°
           80°+z=180°
                 z=180°-80°
                 z=100°
So, The angles are 30°, 50° and 100°.

Answer 2

The sum of two angles is $80^0$. We know that all the three angles of  a triangle adds up to 180. One of them is 20. So subtract.

80-20=60  
180-80=100 

Therefore the angles are 20,60 and 100.