The easiest way to understand what you're doing is to find the area of the base first, then extend it upwards to find the volume using height. Hence the equation: b×h=v
So how do we find the base of a triange? Remember that every single triangle can be calculated as a square, then cut in half. So 9 × 6 / 2 = 27cm2
The next step is to calculate the volume using the height of the figure. 27 × 12 = 324 cm3