We know that the sum of all the three angles of any triangle equals 180 degrees
Now here measure of two angles is given to us and we are asked to fine the measure of third angle
So we can apply the property
So
m∠1 +m∠2 +m∠3 = 180°
58°+122° +m∠3=180°
180° +m∠3 = 180°
subtracting 180° from both sides
we get
m∠3 = 0°
It means the triangle is not possible , it will be a straight line
