 Manipulative 1: Isosceles right triangle. Created with GeoGebra. 

An isosceles right triangle is a
triangle
with one
right angle
where the measures of the other two angles are equal. Since the sum of the angles of a
triangle is 180°, the measure of each of the equal angles is
(180°  90°) ÷ 2 = 45°. Click on the blue points in
manipulative 1 and drag them to change the manipulative.
Properties of isosceles right triangles
 One angle of an isosceles right triangle is a right angle.
 The two base angles of an isosceles right triangle are congruent.
 The two base angles of an isosceles right triangle both measure 45° = π/4 radians.
 The two sides of an isosceles right triangle opposite the base angles are congruent.
 The area of an isosceles right triangle is where b is the length of one of the legs.
 The perimeter of an isosceles right triangle is where b is the length of one of the legs.
