Composite Figures, SM-Bank 008

Find the perimeter of the figure below correct to one decimal place. (2 marks)

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\(114.2\ \text{m (1 d.p.)}\)

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\(\text{Large semi-circle: }\ d_{1}=40,\ \text{Small semi-circle: }\ d_{2}=20\)

\(\text{Perimeter}\)	\(=2\ \text{straight sides}+2\ \text{semi-circles}\)
	\(=2\times 10+\dfrac{\pi d_{1}}{2}+\dfrac{\pi d_{2}}{2}\)
	\(=20+\dfrac{\pi \times 40}{2}+\dfrac{\pi \times 20}{2}\)
	\(=114.2477\dots\)
	\(=114.2\ \text{m (1 d.p.)}\)