a triangle always = how many degrees
Find the third angle of a right triangle. Let's say you know you have a right triangle, with one of the other angles being 30°. If it's a right triangle, then you know that one of the angles measures exactly 90°. The same principles apply. Find the third angle of an isosceles triangle. Isosceles triangles have two equal sides and two equal angles. The equal sides are marked by one hash mark on each of them, indicating that the angles across from each side are equal. We know that the sum of the measures of any triangle is 180 degrees. Using the fact that angle A + angle B + angle C = 180 degrees, we can find the measure of angle C. angle A = 40. angle B = 60. angle C = we don't know. In geometry and trigonometry, a right angle is an angle of exactly 90° (degrees),[1] corresponding to a quarter turn.[2] If a ray is placed so that its endpoint is on a line and the adjacent angles are equal, then they are right angles.[3] The term is a calque of Latin angulus rectus; here rectus means upright, referring to the vertical ... In an isosceles triangle, we have two sides called the legs and a third side called the base. The angle located opposite the base is called the vertex. The vertex angle B of isosceles triangle ABC is 120 degrees. Find the degree measure of each base angle. Find the third angle of an equilateral triangle. An equilateral triangle has all equal sides and all equal angles. It will typically be marked by two hash marks in the middle of each of its sides. This means that the angle measurement of any angle in an equilateral triangle is 60°. Check your work. 60° + 60° + 60° = 180°. The angles of a triangle always sum to 180 degrees. You can use this fact to solve for the missing angle of a triangle. This geometry lesson covers the angles of a triangle, complete with examples and diagrams. Remember -- the sum of the degree measures of angles in any triangle equals 180 degrees. Below is a picture of triangle ABC, where angle A = 60 degrees, angle B = 50 degrees and angle C = 70 degrees. If we add all three angles in any triangle we get 180 degrees. So, the measure of angle A + angle B + angle C = 180 degrees. This is true for any triangle in the world of geometry. We can use this idea to find the measure of angle(s) where the degree measure is missing or not given. How to Find the Third Angle of a Triangle. Three Methods: Using the Other Two Angles Using Variables Using Other Methods Community Q&A. Finding the third angle of a triangle when you know the measurements of the other two angles is easy. All you've got to do is subtract the other angle measurements from 180° to get the measurement of the third angle. Isosceles Triangles Have Two Equal Sides. There are many types of triangles in the world of geometry. There is a special triangle called an isosceles triangle. In an isosceles triangle, the base angles have the same degree measure and are, as a result, equal (congruent). Similarly, if two angles of a triangle have equal measure, then the sides opposite those angles are the same length.
The sum of the degree measures of angles in any triangle equals 180 degrees.