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Here's another question that I am stuck on. I'm not sure how you would find the radius.
O is the centre of a circle of radius r cm and angle AOB = θ = 2 radians.
Given that the shaded area (the area of the sector take away the area of (r²sinθ)/2 (in other words, the triangle part of the sector) equals 20cm².
Find the value of r.
Thank you very much in advance.
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Do I need to substitute θ = 2 radians into the equation?
Because I get:
r²=40/(θ-sinθ)
And I don't know how to continue after that. o_O
Of course. You are given θ = 2. Thus
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Hmm, using what you posted, I got an answer of 4.51cm, whereas the answer in the book is 6.06cm. Perhaps there is a slip up somewhere?
The angles are in radians. Switch your calculator to radians.
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Oh yeah. OMG. >_< I am so silly, I got all the way down to the r² bit fine, I just forgot that they were in radians. Oh dear. I need to make sure not to make the same mistake again.
Thank you.
Youre welcome. The most important thing is that you now understood the whole question.
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Easy mistake to make. You'll stop making it (as much) as you continue to do more maths (mainly because you work in radians pretty much the whole time).
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