Composite Figures, SM-Bank 027

Pedro had one piece of pizza left to eat. The piece of pizza was one-eighth of the whole pizza and had a radius of 12 centimetres.

Calculate the perimeter of Pedro's piece of pizza. Give your answer correct to the nearest centimetre. (2 marks)

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\(89\ \text{cm (nearest cm)}\)

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\(\text{Radius of sector}=12\ \text{cm}\)

\(\text{Perimeter}\)	\(=2\ \text{straight edges}+\dfrac{1}{8}\times \text{circumference} \)
	\(=2r+\Bigg(\dfrac{1}{8}\times 2\pi r\Bigg)\)
	\(=2\times 12 +\Bigg(\dfrac{1}{8}\times 2\pi \times 12\Bigg)\)
	\(=24+\dfrac{24\pi}{8}\)
	\(=80+3\pi\)
	\(=89.424\dots\)
	\(\approx 89\ \text{cm (nearest cm)}\)