## Key Concepts

• Properties of Rectangles
• Rectangles have four sides and four right ($90^\circ$) 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 $180^\circ$.
• $m\angle A+m\angle B+m\angle C=180^\circ$
• 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.
• $A=\Large\frac{1}{2}\normalsize bh$

## 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.