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# help with circles! Watch

1. Hi I was wondering if someone could help with this question

Circle C has the equation (x-4)2 + (y-3)2 = r2

Line L is x=10

i know that the radius is 5.

how do you show that L and C have no points of intersection?

and how do u find the coordinates of the points on the line L which are at a distance of 10 units from the centre C?

any help would be appreciated!! thanks
2. (Original post by t2700)
how do you show that L and C have no points of intersection?
substitute x=10 into the equation, expand the brackets and collect like terms. you'll be left with a quadratic in y. what do you know about this quadratic if there are no points of intersection?
3. (Original post by Pheylan)
substitute x=10 into the equation, expand the brackets and collect like terms. you'll be left with a quadratic in y. what do you know about this quadratic if there are no points of intersection?
(Original post by Pheylan)
substitute x=10 into the equation, expand the brackets and collect like terms. you'll be left with a quadratic in y. what do you know about this quadratic if there are no points of intersection?
thanks for your help
will it hav no roots, so the discriminant will be negative?
4. (Original post by t2700)
thanks for your help
will it hav no roots, so the discriminant will be negative?

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