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# Exam tomorrow really need to ace this Watch

1. So I have done part (a) and (b) just need help with part (c)
2. use the formula for length of line segment (pyhtagoras) and aolve for y using the radius = 5 and x = 13 to find the y coordinates
3. As the line intersects the circle where x = 13, P and Q must have the x coordinate 13. Substitute 13 in for x in the equation for C then solve it.

169 + y^2 - 260 - 16y +139 = 0
y^2 - 16y +48 = 0
(y-12)(y-4) = 0
y= 12 y=4

As P is higher than Q, P has coordinates (13,12) and Q has (13,4)

I hope this is right and it helped!
4. (Original post by chantsmariexx)
As the line intersects the circle where x = 13, P and Q must have the x coordinate 13. Substitute 13 in for x in the equation for C then solve it.

169 + y^2 - 260 - 16y +139 = 0
y^2 - 16y +48 = 0
(y-12)(y-4) = 0
y= 12 y=4

As P is higher than Q, P has coordinates (13,12) and Q has (13,4)

I hope this is right and it helped!
Yeah it is right. I just realised that when I did it I substituted 13 into y not x.

Thanks a lot though!

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