Question

The height of a trapezoid is 6 in. and it’s area is 72 in to the 2nd power. One base of the trapezoid is 6 inches longer than the other base. What are the lengths of the bases? Complete the explanation of how you found your answer.

One base is __ inches for one of the bases and __ inches for the other base.


Use the formula for the area of a trapezoid. Substitute 72 for A and 6 for h and simplify the equation to find __ = (b1 + b2). Use guess and check to find two numbers that add to __ with one number 6 more than the other to get __ inches for one of the bases and __ inches for the other base.

Answer 1

Given:

The height of the given trapezoid = 6 in

The area of the trapezoid = 72 in²

Also given, one base of the trapezoid is 6 inches longer than the other base

To find the lengths of the bases.

Formula

The area of the trapezoid is

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

where, h be the height of the trapezoid

$b_{1}$ be the shorter base

$b_{2}$ be the longer base

As per the given problem,

$b_{2}=b_{1} +6$

Now,

Putting, A=72, $b_{2}=b_{1}+6$ and h=6 we get,

$\frac{1}{2} (b_{1} +b_{1}+6)(6) = 72$

or, $b_{1}+b_{1}+6 = \frac{(72)(2)}{6}$

or, $2b_{1}+6 = 24$

or, $2b_{1}=24-6$

or, $b_{1}= \frac{18}{2}$

or, $b_{1}=9$

So,

The shorter base is 9 in and the other base is = (6+9) = 15 in

Hence,

One base is 9 inches for one of the bases and 15 inches for the other base.