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# C2 beast question wtf is this?

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Why bother with a post grad? Are they even worth it? Have your say! 26-10-2016

1. So me and my friends realized that there are 3 circles, but we have no idea where to go on from there. How'd you do this?
2. woo
3. The sector ABO and the sector COD can be found then subtract these from the semicircle ABCDO
4. Hint 1:
Spoiler:
Show
Split it in to three sections. Should be quite obvious. Try to find the area of each.
Hint 2:
Spoiler:
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If you can't find the area of the two smaller sections, think about triangle OAB - what are the angles/what's the area?
Hint 3:
Spoiler:
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If you've found the area of OAB, what other bits are there to add on? Can you think of a formula to find an area which includes these parts?
5. (Original post by frostyy)

So me and my friends realized that there are 3 circles, but we have no idea where to go on from there. How'd you do this?
Where'd you get this anyway
6. This is but you know the angle theta is 60 degrees because the arcs tell you that the triangle AOB is equilateral.
7. (Original post by shakeebshams)
Where'd you get this anyway
solomon paper L
8. (Original post by frostyy)

So me and my friends realized that there are 3 circles, but we have no idea where to go on from there. How'd you do this?
form 2 equilateral triangles find thier area and minus it by the area of the sectors. Then find the area of the arc in the middle and mius it by the amount you got in the first one and then fiddle around with it and you should get your answer
9. Not much of a beast once you see the two triangles
10. (Original post by Xenon17)
Not much of a beast once you see the two triangles
Can't see the triangle fam.
Need help
11. (Original post by shakeebshams)
Can't see the triangle fam.
Need help
Spoiler:
Show
OAB (and CDO).
12. (Original post by TLDM)
Spoiler:
Show
OAB (and CDO).
So, they're both equilateral? We've got only 1 side
13. I would go with 2 triangles and 2 segments and minus them from the semi circle. And you know the triangles are equilateral because r is the length of all the sides.
14. You split the diagram into 3 Arcs and 3 traingles. Then calculate the area of a segment on the diagram.
15. (Original post by frostyy)

So me and my friends realized that there are 3 circles, but we have no idea where to go on from there. How'd you do this?
loool
16. Ahhhh...
I didn't read it properly
17. If you take the sector OBC, you can find the area πr^2 x 60/360 = 1/6πr^2
If you take the area of the triangle OBC, you get the area 1/2absinC = 1/2r^2sin60 = sqrt3/4 r^2

And it is pretty self explanatory from there, just factorise out 1/6r^2
It is not an easy spot, but fun question anyway
18. C and D lie on circumference, hence OD and OC are radii (and equal). Q says OB & OC are arcs, (centre A and D, respectively) so OD= DC.

if OD=DC=OC (equalateral), <ODC=60. then (area of semi circle- (area of AOB+ area of ODC))
19. Thanks for finding this; I heard about this question and saw my teacher once draw the diagram explaining it for a resit student but never knew the question was a C2 monster.
20. That's a cute question

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