Let s be the shortest side. Using the information you're given, you can create an equation. 27= s + s+3 + 2s. Now just solve the equation. Subtract 3 from both sides. 24=4s. Divide by 4 on both sides. 6=s. So the shortest side is 6 feet long, so we add 3 to that for the one that is neither the shortest or the longest. That side is 9 feet long. We double s to get 12, which is the longest side.
Used desmos, also, in these situations I believe you can take the number inside the brackets and make it negative and keep the number outside the same to find the vertex.
