Question 40531
Draw the triangle out on a piece of paper. You can bisect it to get a right triangle! The right triangle's leg are now: {{{x}}} and {{{5}}} .... the hypotenuse is: {{{13}}}
{{{a^2 + b^2 = c^2}}}
{{{x^2 + 25 = 169}}}
{{{x^2 = 144}}}
{{{x = 12}}} there is your altitude!