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Maths Exercices

Trapezoid properties

Trapezoids are one of the most common quadrilaterals. A trapezoid is a quadrilateral having two, and only two, parallel sides. The bases of the trapezoid are its parallel sides; the legs are its non parallel sides.

When a trapezoid has two sets of parallel sides, it is a more specific type of trapezoid called a parallelogram.

A more specific type of trapezoid is called an isosceles trapezoid. An isosceles trapezoid is a trapezoid with congruent sides.


Trapezoid principles.

  • Principle 1: The lower (and upper) base angles of an isosceles trapezoid are congruent.



  • Principle 2: The diagonals of an isosceles trapezoid are congruent.


Find <A, <D and <C

<A=110º
<C=180º - 110º = 70º (because <B and <C are supplementary angles)
<D=70º