Area, SM-Bank 136 The diagram shows an annulus. Calculate the area of the shaded region (annulus), correct to 2 decimal places. (2 marks) --- 4 WORK AREA LINES (style=lined) --- Show Answers Only \(\approx 50.27\ \text{cm}^2\ (2\text{ d.p.})\) Show Worked Solution \(\text{Method 1:}\) \(\text{Radius small circle}\ (r)=3\) \(\text{Radius large circle}\ (R)=\dfrac{10}{2}=5\) \(\text{Shaded region}\) \(=\text{Area large circle}-\text{Area small circle}\) \(=\pi\times 5^2-\pi \times 3^2\) \(=25\pi-9\pi\) \(=16\pi\) \(=50.27\ \text{cm}^2\ (2\text{ d.p.})\) \(\text{Method 2:}\) \(\text{Area of annulus}\) \(=\pi(R^2 − r^2)\) \(=\pi(5^2 − 3^2)\) \(=\pi(25 − 9)\) \(=16\pi\) \(=50.27\ \text{cm}^2\ (2\text{ d.p.})\)
