The base **angles** (**angles** formed between non-parallel sides and parallel sides) are equal in an **isosceles trapezoid**. Diagonals of an **isosceles trapezoid** are equal in length. The sum of opposite **angles** in an **isosceles trapezoid** is 180 degrees.

Also, are isosceles trapezoids always similar? ABC and ?DEF **are isosceles**, then they are **similar**. This is not true. Both triangles **are isosceles** (since within each triangle, there is a pair of congruent angles), but the triangles are not **similar** (because the angles of one are not congruent to the angles of the other).

Accordingly, what are the properties of an isosceles trapezoid?

Convex polygon Cyclic

Do diagonals bisect angles in an isosceles trapezoid?

Both parallel sides are called bases. Recall that in an **isosceles** triangle, the two base **angles** are congruent. The **diagonals** of an **isosceles trapezoid** are also congruent, but they **do** NOT **bisect** each other. **Isosceles Trapezoid Diagonals** Theorem: The **diagonals** of an **isosceles trapezoid** are congruent.