To be able to answer this, we need an information of either of the legs of the triangle. For this, let me just assume that xy is twice the length of yz.
Area = 1/2 (b)(h) Area = 1/2 (xy) (yz) Area = 1/2 (xy) (1/2xy) 36 = 1/4 (xy)^2 144 = (xy)^2 xy = 12
