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The diagram shows the curve with equation \(y = \ln ( \cos x )\), for \(0 \leqslant x \leqslant 1.5\). The region bounded by the curve, the \(x\)-axis and the line \(x = 1.5\) has area \(A\). The region is divided into five strips, each of width 0.3 .
- By considering the set of rectangles indicated in the diagram, find an upper bound for \(A\). Give the answer correct to 3 decimal places.
- By considering another set of five suitable rectangles, find a lower bound for \(A\). Give the answer correct to 3 decimal places.
- How could you reduce the difference between the upper and lower bounds for \(A\) ?