So first, you have to know Pythagorean theorem. First, you have to know the equation “(a^2)+ (b^2)=c^2” It’s the first two legs squared equals the hypotenuse squared. So the first leg, 12, squared is 144. The second leg, 16, squared is 256. 144+256= 400. Now, we only have 1 more step' which is finding the square root of 400. 20 × 20 = 400, so the length of the missing measure is the 4th answer, 20 yd.
