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# C2 Trigonometry Question Watch

1. Solve the equation tan θ = 2 sin θ for 0◦ ≤ θ ≤ 360◦

I got up to: Sinx/Cosx=2Sinx

the Mark scheme is attached and as always completely useless:
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2. (Original post by TheAlphaParticle)
Solve the equation tan θ = 2 sin θ for 0◦ ≤ θ ≤ 360◦

I got up to: Sinx/Cosx=2Sinx

the Mark scheme is attached and as always completely useless:
Multiply both sides by cos(x), move everything to the same side then take out a factor of sin(x).
3. (Original post by notnek)
Multiply both sides by cos(x), move everything to the same side then take out a factor of sin(x).
What do you mean by that?
4. ^^^^ but then do not cancel out the sinx
5. (Original post by TheAlphaParticle)
What do you mean by that?
Multiply everything by cos(x) gives:
sin(x) = 2sin(x) cos(x)

Take over to one side:
0 = 2sin(x) cos(x) - sin(x)

Take sin(x) outside of the bracket
0 = sin(x)[2cos(x) -1]

Now you have equate each part to 0 and solve:
Let 0 = sin(x)
Let 0 = 2cos(x) -1
6. (Original post by TheAlphaParticle)
What do you mean by that?
Um, you should really know what 'taking out a factor' is by now...
7. Out of interest, why are you currently revising C2? Which exam board are you doing?

Or are you just doing this for fun?
8. (Original post by BasicMistake)
Out of interest, why are you currently revising C2? Which exam board are you doing?

Or are you just doing this for fun?
I do OCR MEI and my C2 is next week. They just reversed the date of S1 and C2
9. (Original post by IrrationalRoot)
Um, you should really know what 'taking out a factor' is by now...
Not everyone learns it the same way, too my knowledge none of my teachers ever used that phrase nor have I ever needed to use it!
10. (Original post by BasicMistake)
Multiply everything by cos(x) gives:
sin(x) = 2sin(x) cos(x)

Take over to one side:
0 = 2sin(x) cos(x) - sin(x)

Take sin(x) outside of the bracket
0 = sin(x)[2cos(x) -1]

Now you have equate each part to 0 and solve:
Let 0 = sin(x)
Let 0 = 2cos(x) -1
Thanks for the detailed explanation!
11. (Original post by TheAlphaParticle)
Not everyone learns it the same way, too my knowledge none of my teachers ever used that phrase nor have I ever needed to use it!
How do you refer to taking out a factor from an expression then?

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