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# Help with Circle question Watch

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1. So I subbed in the x and y values: (-3)2 + (4)2 = 25
Now what do I do?
2. Ok, from the equation you know that the centre of the the circle is at the origin. So now how could you find the gradient of the line between the centre and P?
3. (Original post by ℓove)

So I subbed in the x and y values: (-3)2 + (4)2 = 25
Now what do I do?
If the radius (a line) and the tangent (another line) are perpendicular to eachother... how can you use that info to find the gradient of the tangent?
4. (Original post by ℓove)

So I subbed in the x and y values: (-3)2 + (4)2 = 25
Now what do I do?
You know the centre is (0,0) and the point P(-3,4) so work out the gradient of the radius and the gradient of the tangent is the negative reciprocal as it is perpendicular and then use y=mx+C or y-y1=m(x-x1)
5. (Original post by NotNotBatman)
You know the centre is (0,0) and the point P(-3,4) so work out the gradient of the radius and the gradient of the tangent is the negative reciprocal as it is perpendicular and then use y=mx+C or y-y1=m(x-x1)
Oh yeah forgot the center was (0,0)

Thanksssss

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