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Maths Proof (circles) watch

1. How do you prove that for any circle in a coordinate grid, the line through the circle and the origin goes through the closest point from the edge of the circle to the origin?
2. (Original post by muttonrolls)
How do you prove that for any circle in a coordinate grid, the line through the circle and the origin goes through the closest point from the edge of the circle to the origin?
Suppose that the closest point on the circle is somewhere else. Draw a stright line from the origin to this point, a straight line from this point to the centre of the circle, and a straight line from the centre of the circle to the origin. You now have a triangle. Do you know what the triangle inequality is? This should help you finish the proof.
3. thanks, i got it using the way you described

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