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Point A ii

In this movie we again move A along a line parallel to BC. We show the same three postions of A but now also highlight the resulting base and height each time. As can be seen, except for A1 they have the values 3 and 4 (or 4 and 3), so it easy to see that the area of the triangle is 6 unit squares.

For A1 we get a right-angled triangle but the lengths of the base and height are less straightforward (involving root 10), and also less straightforward than for the right-angled triangle involving C1. We look more closely at this on the next page.