00:02
Okay, this question wants us to find the area of this triangle using determinants.
00:09
So, remember that there's a determinant formula that gives us the area of a triangle with vertices.
00:20
So it says that area is equal to one -half times the determinant of.
00:25
You put all the xs in one column, and then you put all the corresponding ys in the other in order.
00:33
And then you just have a column of ones.
00:36
And this plus or minus is whatever one makes the determinant a positive, because areas are always positive.
00:43
So using this formula, so we have plus or minus one half, times the determinant of, well, let's just list our ordered pairs.
00:59
So we have 0 ,0, 31, and 15.
01:08
And then we have a column of ones...