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Circle C has a radius 5 and touches the y-axis at point (0,9),

(a) write down the equation for the circle C

A line through the point (8,-7) is the tangent to the circle C at the point T
(b) Find the length of PT

Note: The circle in in the upper left quartile if that is any help
p.s could somebody give me a full working out, that way I will understand how to answer this question.

Thank you.
Original post by showaali
(a) write down the equation for the circle C

A line through the point (8,-7) is the tangent to the circle C at the point T
(b) Find the length of PT

Note: The circle in in the upper left quartile if that is any help
p.s could somebody give me a full working out, that way I will understand how to answer this question.

Thank you.


Draw a diagram. The radius of the circle to the point of contact with the axis must be horizontal. You should be able to see what the coordinates of the centre must be. Then use ∗x−a)2+(y−b)2=r2 *x-a)^2+(y-b)^2=r^2 to get equation.
(b) the line joining the centre of the circle to the point (8,-7) will be the hypotenuse of a right angle triangle with the other two sides being the tangent and a radius.

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