00:01
Question they ask us, what is the sum of the areas of all triangles in this figure? the thing that makes this difficult is there are several triangles in this figure.
00:12
So here is one of the triangles outlined in blue.
00:17
Then there is another triangle outlined in green.
00:22
And then there is another triangle outlined in red.
00:28
We're going to start with those.
00:29
So we know that the area of a triangle is 1 half times base times height.
00:36
And so the area of that blue triangle would be 1 half times the base is 1 times the height is 2.
00:44
Now 1 half times 1 times 2 gives you 1.
00:49
In a similar way, the area of the green triangle, 1 half base times height, 1 half times 1 times 2, that's 1.
00:58
And the area of the red triangle, 1 half base times height, 1 half times 1 times 2, that's 1.
01:06
But those are all of the triangles in the figure.
01:11
You see, for example, there is this black triangle...