There is word form(which means write the number down, so lets just say I have the numbers 82,7,and 12. So I'll write eighty-two, seven, and twelve. There's also standard form, so lets say I have the numbers 27 and 15 I'll write 20+ 7, then 10+5.) I hope you got it! Good luck <span />
We see here in the diagram that the base is a. We know this because the height is perpendicular to it. We also know the height is bsin(C) which, when replace h for bsin(C) and a for the base, we get A=absin(C), which is the second option.