pure 2 aqaWatch
We had, earlier in the question, for 5 cute marks out of 60, already established that we have a circle of radius 7, centre (-2, 7).
Find the length of the tangent from the point P(6,8) to the circle.
Now using Pythagoras' theorem:
you want, (root65)^2 - 7^2 = missing side^2
So the answer is root 16
Therefore 4 units:
Hope this satisfies your curiosity. DAN
Seems quite shoddy that ya get 5 marks for completing the square, and finding the radius and the centre of the circle, and you have to do that much work for 4.