A^2 + B ^2 = C^2

A^2 + 24^2 = 26^2

A^2 + 576 = 676

A^2 = 100

A = 10

Now we know all the sides. Time to use Area = .5 x A x B

.5 x 10 x 24 = 120 square feet.

If each square foot costs $10 and we have 120 square feet, you're flying $1200 dollars worth of cloth in the wind. Be careful of pirates with grape shot!