Classifying Triangles By Their Angles Math with Mr J

Welcome to Math with Mr. In this video, I'm going to cover how to classify or name triangles based on their angles. Now, we have three options as far as types of triangles based on angles, and we'll start with acute triangles. That means all three angles are less than 90°. Then we have obtuse triangles. That means one obtuse angle within the triangle. And then lastly, right triangles. That means triangle with one right angle. So, let's go through four examples of triangles and classify or name them based on their angles to get better idea of what all of those types of triangles look like. And we'll start with number one where we have triangle with 40° angle, another 40° angle, and then 100° angle. Now, there are two acute angles there, but for triangle to be an acute triangle, all three have to be less than 90. This 100° angle right here is an obtuse angle. It's greater than 90°. So, if triangle has one obtuse angle, it's automatically an obtuse triangle. So, number one, this would be an obtuse triangle. Number two, we have 25°, 65°, and then this signifies 90° angle. So, we have right angle within that triangle. So, this is an example of right triangle. Number three, we have 45°, 60°, and 75°. So, all three angles are less than 90°. That means this is an acute triangle. And then lastly, number four, we have 48°. 40°, and then 92°. 92°, that angle is obtuse. It's close to 90. It's close to right angle, but it is greater. So, this is an obtuse triangle because 92°, that angle is an obtuse angle. One obtuse angle equals an obtuse triangle. So, number four, obtuse. So, there you have it. There's how you classify or name triangles based on their angles. We have three options. Acute triangles, all three angles less than 90°. Obtuse triangles, one obtuse angle, so that means one angle greater than 90°, and then right triangles, one right angle, so one angle equal to 90°. So, hope that helped. Thanks so much for watching. Until next time, peace.