What is the exact length of the unknown side?

A right triangle appears. One leg is labeled seven. One leg is labeled with a question mark. The hypotenuse is labeled nine.

the square root of twenty

the square root of thirty-two

the square root of sixty-three

the square root of one hundred thirty

Question

What is the exact length of the unknown side?

A right triangle appears. One leg is labeled seven. One leg is labeled with a question mark. The hypotenuse is labeled nine.

the square root of twenty

the square root of thirty-two

the square root of sixty-three

the square root of one hundred thirty

ajprincess · Answer

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Use pythagoras theorem.
$a^2+b^2=c^2$
$7^2+a^2=9^2$
$49+a^2=81$