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Byju's Answer
Standard X
Mathematics
Intersection between Tangent and Secant
In the given ...
Question
In the given figure O is the centre of the circle and AB is a tangent at B. If AB = 15 cm and AC =7.5 cm, find the radius of the circle.
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Solution
Let the radius of the circle be ‘r’ CD = 2r (given, CD is diameter of the circle) AB is tangent to the circle (given)
∴
A
B
2
=
A
C
×
A
D
(
15
)
2
=
7.5
(
7.5
+
2
r
)
15
×
15
=
75
10
(
7.5
+
2
r
)
15
×
15
=
75
10
(
7.5
+
2
r
)
30
=
7.5
+
2
r
22.5
=
2
r
r
=
11.25
c
m
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