Question:
The figure is formed by 2 identical semicircles overlapping each other. The radius of each semicircle is 5 cm. O is the centre of both semicircles. AOB and COD are the diameters. The area of the shaded part OBD is 20 cm² and the perimeter of the shaded part OBD is 18 cm.
(a) Using the calculator value of π, find the area of the figure. Correct your answer to 2 decimal places.
(b) Using π = 22/7, find the perimeter of the figure. Give your answer as a mixed number in the simplest form.
Solution:
![P6 / Nan Hua / 2021 / SA2 / Paper 1 – Q05 [1 mark]](https://i0.wp.com/sgprimaths.com/wp-content/uploads/2022/08/P6_SA2_2021_Nan_Hua_Paper1_Q05-Qns.jpg?resize=400%2C260&ssl=1)
![P6 / Ai Tong / 2020 / SA2 Prelims / Paper 1 – Q12 [2 marks]](https://i0.wp.com/sgprimaths.com/wp-content/uploads/2021/08/P6_SA2_2020_Ai_Tong_Paper1_Q12-Qns.jpg?resize=400%2C260&ssl=1)