if the legs of a right traingle are lengths a and b and they hyptonuse is legnth c then
a²+b²=c²
so
the legs are a and 24
the hyponuse is 26
so
a²+b²=c²
a²+24²=26²
a²+576=676
minus 576 both sides
a²=100
square root both sides
a=10
the length of side a is 10in