check the picture below.
so we can simply split the triangular area into two smaller triangles, notice their base and height.
so, simply, get the area of each triangle, sum them up, and that's the area of the triangular section.
[tex]\bf \stackrel{\textit{yellow triangle}}{\cfrac{1}{2}(6)(6)}~~~~+~~~~\stackrel{\textit{blue triangle}}{\cfrac{1}{2}(6)(2)}[/tex]
