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circle questions core 1

so my question is

1.) a circle has a centre (3,-8) and radius 10
a.) express the equation of the circle. i got (x-3)^2 + (y+8)^2 = 10^2
b.) find the x coordinates where the circle crosses the x axis
Original post by collingridgejack
so my question is

1.) a circle has a centre (3,-8) and radius 10
a.) express the equation of the circle. i got (x-3)^2 + (y+8)^2 = 10^2
b.) find the x coordinates where the circle crosses the x axis


First part is right. So at the x-axis, y coordinate is 0.
Original post by RDKGames
First part is right. So at the x-axis, y coordinate is 0.


how do you know that?
Original post by collingridgejack
how do you know that?


Because that's how geometry works? Any point on the x-axis will have it's y-coordinate as 0. Sketch a small graph and go along the x-axis, you'll see how the y-coordinate is invariant.
Original post by RDKGames
First part is right. So at the x-axis, y coordinate is 0.


I've just realised - its cos if its on the x axis it must be y=0 - do you sub that into the above equation?
Original post by collingridgejack
I've just realised - its cos if its on the x axis it must be y=0 - do you sub that into the above equation?


Makes sense to do so - go for it.
Original post by RDKGames
Makes sense to do so - go for it.


thank yuuuuuu

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