Engineering Board Exam Reviewer · Ptolemy's Theorem and Cyclic Quadrilaterals · medium
A cyclic quadrilateral ABCD has AB=CD=5, BC=6 and AD=14. Find the length of diagonal AC.
- 109
- 9.43
- 12
- 10.44
Answer
D. 10.44
Solution
Ptolemy's theorem: AC· BD=AB· CD+BC· AD=25+84=109. The diagonals are equal in this isosceles trapezoid, so AC2=109 and AC=10.44.
More Ptolemy's Theorem and Cyclic Quadrilaterals questions
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