This article has been viewed 686,467 times. This article has been fact-checked, ensuring the accuracy of any cited facts and confirming the authority of its sources. Because two sides are equal, and one of its interior angles is. There are 9 references cited in this article, which can be found at the bottom of the page. An isosceles right triangle is a right angle triangle with two equal sides and two equal angles. Additionally, David has worked as an instructor for online videos for textbook companies such as Larson Texts, Big Ideas Learning, and Big Ideas Math. In an isosceles right triangle (figure below), A and C measure 45° each, and B measures 90°. After attaining a perfect 800 math score and a 690 English score on the SAT, David was awarded the Dickinson Scholarship from the University of Miami, where he graduated with a Bachelor’s degree in Business Administration. A triangle in which one angle measures 90°, and the other two angles measure 45° each is an isosceles right triangle. With over 10 years of teaching experience, David works with students of all ages and grades in various subjects, as well as college admissions counseling and test preparation for the SAT, ACT, ISEE, and more. David Jia is an Academic Tutor and the Founder of LA Math Tutoring, a private tutoring company based in Los Angeles, California. In this article, we have given two theorems regarding the properties of isosceles triangles along with their proofs.

When the third angle is 90 degree, it is called a right isosceles triangle. It has two equal angles, that is, the base angles. This article was co-authored by David Jia. Some pointers about isosceles triangles are: It has two equal sides.

Isosceles triangle right angle