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Help needed with C2 Solomon Question

I'm stuck on question 2. Even after looking at the mark scheme I'm none the wiser so if anybody could actually tell me the steps to answering the question I'd appreciate it.

https://b940eb267c31463d4d23ccfd3105c3b78e5616c6.googledrive.com/host/0B1ZiqBksUHNYUnQzSHRkZ3JoNGs/for-OCR/Solomon%20L%20QP%20-%20C2%20OCR.pdf
Reply 1
Avatar for bossie
bossie
1
AO, BO, CO, DO all have length r, being radii of the circle
AB and CD also have length r, since they are radii of the arcs OB and OC
Thus ABO and CDO are equilateral triangles of side length r

This means that each sector has an angle of 60 degrees

The shape ABO is composed of a triangle and 2 segments

So shaded region = area of sector - 2 * area of segment

Area of segment = area of sector - area of triangle
Continued on paper
(edited 8 years ago)
IMG_20150506_212146~2.jpg265.1KB
IMG_20150506_212206.jpg239.4KB
Reply 2
Avatar for Azizz
Azizz
OP
4
Thank you so much, I was confused at how to find the angles but now seeing your drawing I realise how obvious it was -.- really appreciate that.

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