Find the unknown side of the right triangle. Round to the nearest thousandths. One side is 9yd, the other side is 12 yd.

You haven't told us whether 9 and 12 are the two legs of the triangle, or whether the 12yd is the longest side.

If the 9 and the 12 are the two legs, then:

C² = A² + B²

C² = 81 + 144

C² = 225

C = 15 yd

If the 12 is the longest side, then:

(12) ² = (9) ² + B²

B² = (12) ² - (9) ² = 144 - 81 = 63

B = √63 = 7.937yd (rounded)