I'm not sure if this is the correct answer. I'm not good with rhombuses! I think what you have to do is cut both diagonals in half.
18 / 2 = 9
24 / 2 = 12
Square them.
9^2
12^2.
Have them add to each other in one of those square root line things.
[tex] \sqrt{9^2 + 12^2} [/tex]
Then find the square root of doing that math! Which should be 15! Hope this helped!
