7. The diagram shows the circle x² + y² = 17.
P lies on the circle and has x-coordinate 1.
The tangent at P intersects the x-axis at R.
Work out the coordinates of R




Answer :

Answer:

  R(17, 0)

Step-by-step explanation:

You want the coordinates of the point R on the x-axis where a tangent to the circle x²+y²=17 meets the circle at P with an x-coordinate of 1.

Secant-tangent relation

If A and B are the points on the x-axis where the circle meets it, the relation between secants and tangents tells us ...

  (RA)(RB) = (RP)²

The point P has x-coordinate 1. Its y-coordinate will satisfy ...

  x² +y² = 17

  y² = 17 -1² = 16

  y = ±4

The distances from point R=(x, 0) to points A, B, and P can be found using the distance formula, or by subtracting x-coordinates.

  [tex](RA)(RB)=(RP)^2\\\\(x-(-\sqrt{17}))(x -\sqrt{17})=(x-1)^2+(0-(4))^2\\\\x^2-17=x^2-2x+17\\\\2x=34\\\\x=17[/tex]

The point R is (17, 0), verified by the geometric construction shown in the attachment.

View image sqdancefan

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