The defining trait of this special type of trapezoid is that the two non-parallel sides (XW and YZ below) are congruent.
![](trapezoid/isosceles/picture.jpg)
Base Angles
The base angles of an isosceles trapezoid are congruent.
![Base Angles of Isosceles trapezoid picture](trapezoid/isosceles/base-angles-picture.jpg)
![Base angles of isosceles trapezoid problem](trapezoid/isosceles/baseAngle1.jpg)
Angle $$ \angle ADC = 44° $$ since base angles are congruent
![Base angles diagram and problem](trapezoid/isosceles/baseAngle3.jpg)
Single $$ \angle ADC = 4° $$ since base angles are congruent
![Base Angles practice Problem](trapezoid/isosceles/baseAngle4.jpg)
J = 5
Diagonals of Isosceles Trapezoid
![Diagonals of Isosceles Trapezoid](trapezoid/isosceles/diag/picture.jpg)
X = 9