The formula of an area of a rectangular triangle:
[tex]A=\dfrac{ab}{2}[/tex]
a, b - a leg
[tex]A=\dfrac{5\cdot12}{2}=\dfrac{60}{2}=30\ mi^2\\\\A=\dfrac{13\cdot x}{2}[/tex]
We have the equation:
[tex]\dfrac{13x}{2}=30\ \ \ |\cdot2\\\\13x=60\ \ \ |:13\\\\x=\dfrac{60}{13}\\\\x\approx4.6\ mi[/tex]
Answer: 4.6 mi
