Course 2

9-4 Area of Triangles and Trapezoids

AREA OF A TRIANGLE

h

b

A = 12

bhThe area A of a triangleis half the product of itsbase b and its height h.

Course 2

9-4 Area of Triangles and Trapezoids

AREA OF A TRAPEZOID

h

b1

A = 12

h(b1 + b2)

The area of a trapezoid is half its height multiplied by the sum of its two bases.

b2

In the term b1, the number 1 is called a subscript. It is read as “b-one” or “b sub-one.”

Reading Math

Course 2

9-2 Perimeter and Circumference

Radius

Diameter

Circumference

C = d, or C = 2r

CIRCUMFERENCE OF A CIRCLE

The circumference C of a circle is times the diameter d, or 2 times the radius r.

SURFACE AREA OF A PRISM

The surface area of a rectangular prism is the sum of the areas of each face.

S = 2lw + 2lh + 2wh

SURFACE AREA OF A CYLINDER

The surface area S of a cylinder is the sum of the areas of its bases, 2r2, plus the area of its lateral surface, 2rh.

S= 2r2 + 2rh

The volume of a rectangular prism is the area of its base times its height. This formula can be used to find the volume of any prism.

VOLUME OF A PRISM

The volume V of a prism is the area of its base B times its height h.

V = Bh

Finding the volume of a cylinder is similar to findingthe volume of a prism.

VOLUME OF A CYLINDER

The volume V of a cylinder is the area of its base, r2, times its height h.

V = r2h

In fact, the volume of a pyramid is exactly one-third the volume of a prism if they have the same height and same-size base. The height of a pyramid is the perpendicular distance from the pyramid’s base to its vertex.

Course 2

10-3 Volume of Pyramids and Cones

The volume of a cone is one-third the volume of a cylinder with the same height and a congruent base. The height of a cone is the perpendicular distance from the cone’s base to its vertex.

Course 2

10-3 Volume of Pyramids and Cones