Question

Find the length of the missing side of the trapezoid below.

Answer 1

Answer:

2√10

Step-by-step explanation:

Draw a vertical line through the corner between the side of length 7 and the side of length 5.  This line forms a right triangle with hypotenuse 7 and base (8 - 5), or 3.

The Pythagorean Theorem applies here.  

(hypotenuse)² = (base)² + (vertical side)²    and this becomes:

          7² = 3² + (vertical side)²

Solving this for (vertical side)², we get (vertical side)² = 49 - 9 = 40.

Thus, (vertical side) = √40 = √4·√10 = 2√10 (answer)