解设较长直角边为x,较短的为(x-1)
则 x(x-1)÷2×4+1²=13
2x²-2x-12=0
x²-x-6=0
(x-3)(x+2)=0
x-3=0 x+2=0
x1=3 x2= -2(舍去)
答这些直角三角形中较长直角边的长是3