The property of a triangle: the sum of all angles in the triangle is equal to 180°. An isosceles triangle has two angles of the same measure at the base. The right triangle has one angle that measures 90°. So the sum of two other angles is equal to 180° – 90° = 90°. Let one angle be equal to x°. So the other angle is equal to x° too. We can write the equation:
x + x = 90° X = 45°
So the measures of the angles are: 90°, 45°, 45°.