9. The diagonal BD divides quadrilateral ABCD into a right triangle and an equilateral triangle, as shown below. The given dimensions are in centimeters. How many centimeters long is AD?

Answer and Explanation

Your Answer is

Correct Answer is C

Explanation

According to the Pythagorean theorem (a2+b2=c2), the lengths of CD and CB are 6 and 8 respectively , the length of the hypotenuse BD is the root of the sum of the squares of the lengths of the two sides, which is 10. The three sides of an equilateral triangle are equal, so the length AD is 10. Choose C.