Answer:
QR = 15
Explanation:
The product of the length of the secant segment and its external part equals the square of the length of the tangent segment.
(QR+5) *5 = 10^2
(QR+5) *5 = 100
Divide each side by 5.
(QR+5) *5/5 = 100/5
(QR+5) = 20
Subtract 5 from each side.
QR = 20-5
QR = 15