The length of PR = 18 .
A chord is a line segment whose both points lie on the circle.
When a chord is extended it is called secant .
When two chords meet outside the circle , the product of length of the secant and its external segment is equal to the product of length of other secant and its external segment.
According to the given data
FR and FP are the secants of the circle
To determine the measure of PR
From the secant theorem
(7+9) * 9 = (5x+8) * 8
16 * 9 = (5x+8) *8
2 *9 = 5x+8
18 = 5x+8
5x = 10
x = 2
Therefore the length of PR = 5x+8 = 10+8 = 18
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