Question

What is the value of a?

Answer 1

a = 16

Explanation:

Look at the picture.

The formula of an area of a trapezoid is:

`A=(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=(a+2+a-2)/(2)\cdot8\\\\128=(2a)/(2)\cdot8`

`128=8a` divide both sides by 8

`16=a\to a=16`