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# C2 Coordinate Geometry watch

1. The point A(-3,-7) lies on the circle centre (5,1). Find the equation of the tangent to the circle at A.
2. (Original post by Bevin)
The point A(-3,-7) lies on the circle centre (5,1). Find the equation of the tangent to the circle at A.
What have you tried/are your thoughts?
3. You need to find the other point that makes the line, then plug in the values of midpoint to get the second point. Then get a gradient. Remember that perpendicular lines are negative reciprocal and then form an equation.

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4. if you didn't figure it out yet

m1 (AC) = 8/8 = 1
since we're finding the tangent it's the perpendicular gradient we need to find so m1m2=-1
m2 = -1

then use y-y1=m(x-x1) with m2 and at point A
y+7=-1(x+3)

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