Use the Triangle Angle Sum Theorem to find the measure of the third angle if the first and second angle measure 63°

Question

and 40°
.

Answer 1

The Triangle Angle Sum Theorem states that the sum of the angles in a triangle is always 180°.

So, if the first angle measures 63° and the second angle measures 40°, we can find the measure of the third angle by subtracting the sum of the first two angles from 180°.

Third angle = 180° - (63° + 40°)
Third angle = 180° - 103°
Third angle = 77°.