Composite Figures, SM-Bank 012

Find the perimeter of the figure below giving your answer as an exact value in terms of \(\large \pi\). (2 marks)

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\((84+70\pi)\ \text{cm}\)

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\(\text{Fraction of circle}=\dfrac{360-60}{360}=\dfrac{300}{360}=\dfrac{5}{6}\)

\(\text{Perimeter}\)	\(=2\ \text{radii}+\dfrac{5}{6}\times\text{circumference}\)
	\(=2\times 42+\dfrac{5}{6}\times 2\pi r\)
	\(=84+\dfrac{5}{6}\times 2\pi \times 42\)
	\(=(84+70\pi)\ \text{cm}\)