Question 169769
one leg is 12000, the hypotenuse is 13000. The other leg is the altitude.
{{{13000^2 = 12000^2 + A^2}}}
{{{13000^2 - 12000^2 = A^2}}}
This is a variation on the 5-12-13 right triangle. You'll want to 'recognize' them (just like you ought to recognize a 3-4-5)