Instructions

[Turn over

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8
7
1
6
π
rad
2
r
r
r
O
A
B
C
In the diagram,
OAB
is a sector of a circle with centre
O
and radius 2
r
, and angle
AOB
=
1
6
π
radians.
The point
C
is the midpoint of
OA
.
(a)
Show that the exact length of
BC
is
r
5
−
2
3.
[2]
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© UCLES 2020
9709/12/M/J/20

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