Question

What is the value of a?

Answer 1

Answer:

a = 16

Step-by-step explanation:

Look at the picture.

The formula of an area of a trapezoid is:

$A=\dfrac{b_1+b_2}{2}\cdot h$

$b_1,\ b_2$ - bases

$h$ - height

We have:

$A=128,\ b_1=a+2,\ b_2=a-2,\ h=8$

Substitute:

$128=\dfrac{a+2+a-2}{2}\cdot8\\\\128=\dfrac{2a}{2}\cdot8$

$128=8a$          divide both sides by 8

$16=a\to a=16$