# Question d575c

Dec 7, 2016

The formula for a rectangle is A=bh. A trapezoid has a different top and bottom, but a constant height. If you average the top and bottom lengths $\frac{\left(b 1 + b 2\right)}{2}$, you can use this as the base and find the area of the trapezoid.

#### Explanation:

The official formula is A = ½ h (b1+b2).# This is the same thing, but rearranged. It is easier than it looks.

Apr 19, 2017

$\textcolor{b l u e}{h} = \frac{2 A}{\left({b}_{1} + {b}_{2}\right)}$

#### Explanation:

To change the formula around, I like to have the 'subject' on the left side first and then keep it there, getting rid of all the other variables and numbers bit by bit.

$\frac{1}{2} \textcolor{b l u e}{h} \left({b}_{1} + {b}_{2}\right) = A$

To get rid of $\frac{1}{2}$, multiply both sides by $2$ and cancel.

$\cancel{2} \times \frac{1}{\cancel{2}} \textcolor{b l u e}{h} \left({b}_{1} + {b}_{2}\right) = 2 \times A \text{ }$ this leaves:

$\textcolor{b l u e}{h} \left({b}_{1} + {b}_{2}\right) = 2 A$

Now, to get the $\textcolor{b l u e}{h}$ on its own, divide by the whole bracket.

$\textcolor{b l u e}{h} = \frac{2 A}{\left({b}_{1} + {b}_{2}\right)}$