A quadrilateral ABCD is circumscribed about a circle. The sides of the quadrilateral are tangent to the circle. If the lengths of the sides are given as AB = 9 cm, BC = 12 cm, and CD = 11 cm, what is the length of the fourth side, AD?
Show answer & explanation
Correct answer: A
Explanation
Given:
AB = 9 cm
BC = 12 cm
CD = 11 cm
The quadrilateral is circumscribed about a circle.
By the formula:
In the circumscribed quadrilateral
AB + CD = BC + AD
9 + 11 = 12 + AD
20 = 12 + AD
AD = 8 cm