Take your base length and divide it by two.
Use the Pythagorean theorem.
a^2 + b^2 = c^2
24^2 + 7^2 = c^2
576 + 49 = c^2
625 = c^2
25 = c
Now double that to get the length of both missing sides
25 x 2 = 50
Add that to your base
50 + 48 = 98ft
And you have your answer.
Hop that helped