ISEE Upper Level Math : How to find the length of the diagonal of a kite

Study concepts, example questions & explanations for ISEE Upper Level Math

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Example Questions

Example Question #51 : Quadrilaterals

A kite has the area of \(\displaystyle 60\ in^2\). One of the diagonals of the kite has length \(\displaystyle 15\ in\). Give the length of the other diagonal of the kite.

Possible Answers:

\(\displaystyle 5\ in\)

\(\displaystyle 6\ in\)

\(\displaystyle 8\ in\)

\(\displaystyle 4\ in\)

\(\displaystyle 7\ in\)

Correct answer:

\(\displaystyle 8\ in\)

Explanation:

The area of a kite is half the product of the diagonals, i.e.

\(\displaystyle Area=\frac{d_{1}d_{2}}{2}\),

where \(\displaystyle d_{1}\) and \(\displaystyle d_{2}\) are the lengths of the diagonals. 

\(\displaystyle Area=\frac{d_{1}d_{2}}{2}=\frac{{15}\times {d_{2}}}{2}=60\Rightarrow d_{2}=\frac{60\times 2}{15}\Rightarrow d_{2}=8\ in\)

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