Mathematics » Math Models and Geometry I » Use Properties of Rectangles; Triangles; and Trapezoids

Key Concepts

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.
      • \(A=\frac{1}{2}bh\)

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.

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