Hypotenuse is 26 mm so if we use the p theorem a^2+b^2 = c^2 and theyre giving us c (26mm) and theyre giving us one leg (10mm) just plug it in and solve for the missing variable 10^2 +b^2 = 26^2 100+b^2 =676 b^2 = 576 square root of both sides to solve for b b = plus or minus 24 But the length cannot be a negative length so the answer is b = +24
