Exercise 3 Page 299

Let's find the area of the given trapezoid. The area of a trapezoid is one half the product of the height and the sum of the bases.

Let's rotate the figure to make it easier to see the height and the bases!

We can see that the height of the trapezoid is

5

millimeters

and the bases are

4

millimeters

and

8

millimeters .

We can substitute these values into the formula for the area of a trapezoid. Let's do it!

A = \frac{1}{2} h (b_{1} + b_{2})

Substitute values

A = \frac{1}{2} \cdot 5 \cdot (4 + 8)

▼

Evaluate right-hand side

Add terms

A = \frac{1}{2} \cdot 5 \cdot (12)

A = \frac{1}{2} \cdot 60

$\frac{1}{b} \cdot a = \frac{a}{b}$

A = \frac{6 0}{2}

Calculate quotient

A = 30

The area of the trapezoid is

30

square millimeters.