# O is the centre of the circle .if AB = 8cm and OP = 3cm then find the radius of the circle.

2
by Deleted account
could u please give some more details
means about the point p and the line ab
Thts all I know sis..plzz.. answer ..naaa
its in complete question

2015-03-02T19:41:47+05:30

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See the figure.

AB is the chord.
OP is the perpendicular distance of chord AB from centre

OA is the radius = r
OP = 3cm
AP = 8/2 = 4cm

In the right angled triangle OAP
OA² = OP² + AP²
⇒ r² = 3² + 4²
⇒ r² = 25
⇒ r = √25 = 5cm

:)
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How do you insert a picture in the answer?
AB CAN NEVER LIE WITHIN THE CIRCLE.IT IS LONGER THAN THE DIAMETER,WHICH IS THE LONGEST CHORD.
THE ABOVE CONDITION IS ONLY TRUE IF OA=rADIUS
2015-03-03T09:57:47+05:30
See pic for reference.

OP is perpendicular to AB.
So, OP is also bisector of AB.
So, AP =4 cm

In right-angled triangle AOP,

=
= 9+16
=25
So, AO = √25
= 5 cm

The radius is 5 cm long.