Answer with explanation:
In the problem , given about triangle, four angles are given , r,x ,y and z.
→→One of the three, must be exterior angle of triangle ABC, and other three, must be interior angles of Δ ABC.
So, two properties of triangle that we will use in this problem
1. Angle sum property of triangle: the sum of three angles of triangle is 180°.
2.Exterior angle property: Exterior angle of a triangle is equal to sum of two interior opposite angles.
So, if x, y and z are interior angles , and r is exterior angle
then
Option 3: x + y + z = 180° is always true.
either, r= y + z
and ,r +x=180°
