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In the given figure, QR is a common tangent to the given circles, touching externally at the point T. The tangent at T meets QR at P. If PT = 3.8 cm then the length of QR is
Let the bigger circle be C1 and Smaller be C2,
Now,
PQ and PT are two tangents to circle C1,
∴ PT = QP
[Tangents drawn from an external point are equal]
QP = 3.8 cm
[ As PT = 3.8 cm is given]
Also,
PR and PT are two tangents to circle C2,
∴ PT = PR
[Tangents drawn from an external point are equal]
PR = 3.8 cm
[ As PT = 3.8 cm is given]
QR = QP + PR = 3.8 + 3.8 = 7.6 cm