Answer to Question #92763 in Geometry for Yasmine

Question

While finding a measure of an angle, what do I do if one of the angles inside of the triangle does not have a number but the outside angle does?

Answer 1

On the figure below, Angle 4 is the exterior angle for Angle 3. The sum of measures of the Angle 3 in the triangle and the exterior Angle 4 is 180 degrees.

For the exterior angle of the triangle, the following statement holds: the measure of the exterior angle of the triangle is equal to the sum of measures of the interior angles that are not adjacent to it. On the figure below, Angle 4 = Angle 1 + Angle 2.