Master the 7 pillars of school success that I have learned from 25 years of teaching.

Improve your grades and lower your stress

Can the exterior angles of a triangle be acute?

Yes If the interior angle of the triangle is obtuse then the outside angle will be acute. Conversely, if the interior angle is acute then the exterior angle of the triangle will be obtuse.

The measure of an exterior angle of a triangle is equal to the sum of the measures of the two non-adjacent interior angles

The measure of an exterior angle of a triangle is greater than either of the two remote interior angles.

The measure of the exterior angle is supplementary to the interior angle.

The Exterior Angle is the angle between one side of a triangle, and a line extended from the adjacent side.

Exterior Angle .

Interior Angle .

What is an exterior angle?

Exterior Angle

Remote Interior Angles

Remote Interior Angles

The remote interior angles of a triangles are the two angles that are not adjacent to the exterior angle.The remote interior angles do not share the vertex of the exterior angle.

The measure of the Exterior Angle is equal to the sum measure of the remote interior angles

Hi Welcome to MooMooMath. Today we are going to look at the measure of the exterior angle of a triangle. We have a triangle right here and we only know one angle. Which angles of the triangle are the exterior angles and which are the interior angles? The interior angles are the three angles on the inside of the triangle. To create an exterior angle, I will go to the vertex, and I’m going to extend this side out. This creates an exterior angle that is associated with this 45 degree interior angle, and we know lines add up to 180. So these two add up to what we call a linear pair, they are supplementary, so I can find this exterior angle measure by taking 180 and subtracting 45 so we end up with 135 degrees. It is an obtuse angle so this angle is 135 degrees. So let’s look at the rules for finding exterior angles in a triangle. First, you have to create the exterior angle by extending one side of the triangle. Next, the measure is supplementary to the interior angle. For example, the interior angle is 30, we extend this side out creating an exterior angle, and we find the measure of the angle by subtracting 180 -30 =150. Therefore, we have a 150 degree exterior angle. Hope this was helpful.