The altitude of the triangle would be another line added to the triangle which bisects angle B. We are calling this side h. Looking at the right triangle this added side forms, with respect to angle C, "h" would be the opposite side and "a" would be the hypotenuse. We know that sin∅ = opposite/hypotenuse, so the first blank is:
sinC = h/a
For the second blank, we need to redefine side h. We know sinC = h/a, so let's rearrange that to solve for h:
h = a*sinC
If we substitute a*sinC for h is 0.5*b*h, we get:
Area = 1/2 * b(asinC)
Finally, according to the commutative property of multiplication, the order of terms being multiplied doesn't matter. Therefore the final blank is:
Area = 1/2 * ab(sinC)