Exercise 2 Page 844

The volume of a pyramid can be calculated using a known formula. V=1/3Bh In this formula B is the area of the base, and h is the height. Let's find the area of the base. The base of the pyramid is a pentagon. Recall that a pentagon can be divided into 5 congruent triangles.

To calculate the area of the pentagon we will start with calculating the area of one triangle. Then we will multiply it by 5.

A=1/2ah

SubstituteValues

Substitute values

A=1/2( 4.4)( 3)

▼

Simplify right-hand side

Multiply

Multiply

A=1/2(13.2)

MoveRightFacToNumOne

1/b* a = a/b

A=13.2/2

CalcQuot

Calculate quotient

A=6.6

The area of one triangle is 6.6 square centimeters. Now we can calculate the base area by multiplying this value by 5. B=5( 6.6)=33 We found that the base area is 33 cm^2. We are also given that height of the cone is 12 cm. Let's substitute these values into the volume formula.

V=1/3Bh

SubstituteII

B= 33, h= 12

V=1/3( 33)( 12)

▼

Simplify right-hand side

Multiply

Multiply

V=396/3

CalcQuot

Calculate quotient

V=132

The volume of the pyramid is 132 cm^3.