Chapter 4 - Congruent Triangles - 4-5 Isosceles and Equilateral Triangles - Practice and Problem-Solving Exercises - Page 256: 43

We can use the SAS theorem to prove the triangles are congruent. From the diagram, we can see that one side of each triangle is marked congruent. There is a right angle formed by those congruent sides, so the angles are congruent. The other side forming the right angle is shared by both triangles, so that side is, of course, congruent. So we have two sides and an included angle congruent in the two triangles, so the SAS theorem applies to this problem.

We can use the SAS theorem to prove the triangles are congruent. From the diagram, we can see that one side of each triangle is marked congruent. There is a right angle formed by those congruent sides, so the angles are congruent. The other side forming the right angle is shared by both triangles, so that side is, of course, congruent. So we have two sides and an included angle congruent in the two triangles, so the SAS theorem applies to this problem.