## Key Concepts

**Properties of Rectangles**- Rectangles have four sides and four right (90°) angles.
- The lengths of opposite sides are equal.
- The perimeter, \(P\), of a rectangle is the sum of twice the length and twice the width.
- \(P=2L+2W\)

- The area, \(A\), of a rectangle is the length times the width.
- \(A=L\cdot W\)

**Triangle Properties**- For any triangle \(\Delta ABC\), the sum of the measures of the angles is 180°.
- \(m\angle A+m\angle B+m\angle C=180°\)

- The perimeter of a triangle is the sum of the lengths of the sides.
- \(P=a+b+c\)

- The area of a triangle is one-half the base, b, times the height, h.
- \(A=\frac{1}{2}bh\)

- For any triangle \(\Delta ABC\), the sum of the measures of the angles is 180°.

## Glossary

### area

The area is a measure of the surface covered by a figure.

### equilateral triangle

A triangle with all three sides of equal length is called an equilateral triangle.

### isosceles triangle

A triangle with two sides of equal length is called an isosceles triangle.

### perimeter

The perimeter is a measure of the distance around a figure.

### rectangle

A rectangle is a geometric figure that has four sides and four right angles.

### trapezoid

A trapezoid is four-sided figure, a quadrilateral, with two sides that are parallel and two sides that are not.