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Method A1

Here we reduce the size of the circle through C.
As can be seen, the situation is not defined for all sizes of the circle.

This effect can be quite dramatic, and it is a good principle, to check the generality of a situation. But beyond that, does it help us solve the task? Probably not, though it is useful to note that where QP and QF are defined, they do look as though they might be equal in length.

On the next page we increase the relative size of the circle through C. Can you predict what happens?