Rule: In a triangle, the sum of the three interior angles always is 180° (degrees).
A. 60, 60, 60. If we sum Angle A + Angle B + Angle C= 180 degrees. Thence, this is a triangle with all three internal angles congruent to each other and are each 60°. This triangle is called equilateral.
B. 90, 90 ,45. If we sum Angle A + Angle B + Angle C= 225 degrees. Thence, this is not possible to draw as a triangle.
C. 30, 40, 50. If we sum Angle A + Angle B + Angle C= 120 degrees. Thence, this is not possible to draw as a triangle.
D. 90, 45, 45. If we sum Angle A + Angle B + Angle C= 180 degrees. Thence, this is a triangle with one angle of 90 degrees ir right angle. That is why we call this a rectangular triangle.
E. 120. 30, 30. If we sum Angle A + Angle B + Angle C= 180 degrees. Thence, this is a triangle.
