# Warm Up The lengths of three sides of a triangle are given. Classify the triangle. 1. 12, 12, 12 2. 18, 10, 14 3. 15, 15, 26 equilateral scalene isosceles.

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Warm Up The lengths of three sides of a triangle are given. Classify the triangle. 1. 12, 12, 12 2. 18, 10, 14 3. 15, 15, 26 equilateral scalene isosceles

Learn to identify, classify, and compare quadrilaterals.

Vocabulary quadrilateral parallelogram rectangle rhombus square
trapezoid

A quadrilateral is a plane figure with four sides and four angles.
Five special types of quadrilaterals and their properties will be shown in this lesson. The same mark on two or more sides of a figure indicates that the sides are congruent.

Opposite sides are parallel and congruent
Opposite sides are parallel and congruent. Opposite angles are congruent. Parallelogram Parallelogram with four right angles. Opposites sides are parallel and congruent. Rectangle

Parallelogram with four congruent sides. Opposite angles are congruent.
Rhombus Rectangle with four congruent sides. All angles are right angles. Square

Quadrilateral with exactly two parallel sides
Quadrilateral with exactly two parallel sides. May have two right angles. Trapezoid

Give the most descriptive name for each figure. There are two parallel sides. There are no congruent angles. The figure is a quadrilateral and a trapezoid. Trapezoid is the most descriptive name.

Give the most descriptive name for each figure. There are four congruent sides and four right angles. The figure is a quadrilateral, a parallelogram, and a rectangle. Rectangle is the most descriptive name.

Give the most descriptive name for each figure. The figure is a plane figure with three congruent sides. Equilateral triangle is the most descriptive name.

Give the most descriptive name for each figure. There are four congruent sides, and opposite angles are congruent. The figure is a quadrilateral, parallelogram, and rhombus. Rhombus is the most descriptive name.

There are two parallel sides. There are no congruent angles.
Check It Out: Example 1A Give the most descriptive name for each figure. There are two parallel sides. There are no congruent angles. The figure is a quadrilateral and a trapezoid. Trapezoid is the most descriptive name.

There are two pairs of congruent sides.
Check It Out: Example 1B Give the most descriptive name for each figure. There are two pairs of congruent sides. The figure is a quadrilateral and parallelogram. Parallelogram is the most descriptive name.

This figure is an isosceles triangle.
Check It Out: Example 1C Give the most descriptive name for each figure. The figure is a plane figure with three sides, two of them being congruent. This figure is an isosceles triangle.

There are four congruent sides.
Check It Out: Example 1D Give the most descriptive name for each figure. There are four congruent sides. The figure is a quadrilateral and parallelogram. Parallelogram is the most descriptive name.

You can draw a diagram to classify quadrilaterals based on their properties.