6.
\begin{figure}[h]
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\caption{Figure 1}
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\end{figure}
Fig. 1 shows a gardener's design for the shape of a flower bed with perimeter \(A B C D . A D\) is an arc of a circle with centre \(O\) and radius \(5 \mathrm {~m} . B C\) is an arc of a circle with centre \(O\) and radius \(7 \mathrm {~m} . O A B\) and \(O D C\) are straight lines and the size of \(\angle A O D\) is \(\theta\) radians.
- Find, in terms of \(\theta\), an expression for the area of the flower bed.
Given that the area of the flower bed is \(15 \mathrm {~m} ^ { 2 }\),
- show that \(\theta = 1.25\),
- calculate, in m , the perimeter of the flower bed.
The gardener now decides to replace arc \(A D\) with the straight line \(A D\).
- Find, to the nearest cm , the reduction in the perimeter of the flower bed.