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# Help

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5. Show that the point P(-3,2) lies on the circle (x-1)^2 + (y+2)^2 = 32. Find the tangent to the circle at P.

6. The line 3x - y = 3 is tangent to the circle with centre (5,-1) and radius r. Find the value of r

Oct 16, 2018

### 5+0 Answers

#1
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Don't you know how to show that that point is on the circle?

Oct 16, 2018
#4
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Mmm that should be a concern to you.

Substitute x=-3 and y=2 into the equation and see if the left side is equal to the right side.

If it is then (-3,2) satisfies the equation which means (-3,2) lies on the circle.

1) Now you can do that bit by yourself.

2) Now you need to know the centre of the circle. (look up the equation of a circle and see if you can work that out yourself)

3)Find the gradient of the line joining the centre to the point P

4)The tangent will be at right angles to this radius so what is its gradient?

5) Now you have a gradient and a point on the tangent so you can find the equation of this line.

Oct 16, 2018
#5
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Why havn't you responded?  :/

Melody  Oct 17, 2018