What is the area a triangle with the measurements of 6 and 9?

There is not enough information to answer this question. The measurements could apply to the sides, altitudes, or other characteristics of the triangle, such as the perimeter.

If the measurements are of a base and altitude, then using the area formula for a triange, which is one half the base times the altitude, we would get an answer of (1/2)*6*9 = 27

in whatever units of measurement that were used. (I am assuming that the units are the same for both measurements.)