Hello, alibond07!
You need to know the area of a circle and some common sense.
Exactly where is your difficulty?
A circular dartboard is divided into 20 equal sectors,
one of which is shown in the diagram. O is the centre of the circle.
The areas for scoring double and treble are marked A and B respectively.
Find the ratio (area A) : (area B) in the form n : 1, giving n correct to 1 d.p
OM: 99mm . MN: 8mm . OP: 162mm . PQ: 8mm This is a diagram of the radii: Code:
: - - - - 107 - - - :
: - - -99 - - :
(A) (B)
O ----------- M --- N ------- P --- Q
: - - - - - - - 162 - - - - - :
: - - - - - - - - 170 - - - - - - - :
The circle with radius has area: .
The circle with radius has area: .
. . The area of ring is: .
The circle with radius has area: .
The circle with radius has area: .
. . The area of ring is: .
Hence: .
Therefore: .