Question

the length of the longer leg of a right triangle is 3 ft more than three times the length of the shorter leg. the length of the hypotenuse is 4 ft more than three times the length of the shorter leg. find the side lengths of the triangle.

Answer 1

with the pythagorean theorem

$\begin{gathered} (4+3x)^2=x^2+(3+3x)^2 \\ 16+24x+9x^2=x^2+9+18x+9x^2 \\ 16+24x+9x^2=10x^2+18x+9 \\ 16+24x+9x^2-9=10x^2+18x+9-9 \\ 9x^2+24x+7=10x^2+18x \\ 9x^2+24x+7-18x=10x^2+18x-18x \\ 9x^2+6x+7=10x^2 \\ 9x^2+6x+7-10x^2=10x^2-10x^2 \\ -x^2+6x+7=0 \end{gathered}$

using the formula of the quadratic equation

$\begin{gathered} x_{1,\: 2}=\frac{-b\pm\sqrt{b^2-4ac}}{2a} \\ x1=\frac{-6+\sqrt{6^2-4\left(-1\right)\cdot\:7}}{2\left(-1\right)}=-1 \\ x2=\frac{-6-\sqrt{6^2-4\left(-1\right)\cdot\:7}}{2\left(-1\right)}=7 \end{gathered}$

the length cannot be negative, therefore x=7

length of the shorter leg is: 7ft

length of the longer leg is: 3+3(7)= 24ft

length of the hypotenuse is: 4+3(7)= 25ft