Answer:
9 yards
Explanation:
The Pythagorean theorem:
![a^2+b^2=c^2](https://img.qammunity.org/2022/formulas/mathematics/college/a7evvahf9asnkyok9myxuf24e8ciywglc7.png)
Where a and b are legs, and c is the hypotenuse.
The hypotenuse is the side opposite from the right angle in the right triangle.
The hypotenuse would be AC, measured 15 yards, because it is opposite from the right angle. BC, the unmeasured side would be a leg. I can call that the "b" leg and AB, the 12 yard side the "a" leg.
Substitute the measures into the theorem to get:
![12^2+?^2=15^2](https://img.qammunity.org/2022/formulas/mathematics/high-school/ipd4pvfl6rynptxkunql11j9uqpi06orx1.png)
![144+?^2=225 ; ?^2=81; ?=√(81) =9](https://img.qammunity.org/2022/formulas/mathematics/high-school/qoi7d2in1xpbgvj1fk3jm47esb1y0r74wb.png)