Trapezoid Area 1.375 cm²: Find the Red Side Length

Question

The area of the trapezoid in the diagram is 1.375 cm².

Work out the length of the side marked in red.

00:00 Find AB

00:03 We'll use the formula for calculating trapezoid area

00:07 ((Sum of bases(AB+DC) multiplied by height(H)) divided by 2

00:16 We'll substitute the appropriate values according to the given data and solve for AB

00:29 Multiply by 2 to eliminate the fraction

00:45 Multiply by the reciprocal

00:54 Isolate AB

01:05 And this is the solution to the problem

The area of the trapezoid will be equal to: $S=\frac{(AB+DC)}{2}\times h$

We insert the available data into the formula:

$1.375=\frac{AB+4}{2}\times0.5$

We then multiply by 2 in order to remove the fraction:

Lastly we again multiply by 2:

$5.5=AB+4$

$5.5-4=AB$

$1.5=AB$

$1.5$ cm