What is the angle measure for a triangle?

Answer 1

The angle measure of a triangle is dependent on the type of triangle (scalene, right, isosceles, or equilateral) and also the measures of the other two angles.

In a scalene, none of the angles can be predicted without a protractor because none of the angles are equal.

In a right triangle only one angle can be undoubtedly determined, the 90° angle (right angle). Knowing this angle's measure, this only limits the possible angle measures of the other two angles. (They must each be less than 90°, but together sum up to 90°)

If you know one of the base angles of an isosceles triangle, by the Isosceles Triangle Base Angles Theorem, the other base angle will be congruent. To find the last angle, add the base angles together and then subtract that number from 180.

The only triangle that has angle measures that can be determined just by its name is an equilateral, all angle measures equal 60°.