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# Anyone need help with any *EDEXCEL* C3 and C4 past paper questions? watch

1. sin 3θ=sin (2θ+θ )=sin 2θ cosθ+cos 2θ sinθ

how did the mark scheme get that answer?
i know by expanding the brackets you get sin2θ+ sinθ
and with the sin2θ you use a double angle formula.
but not so sure how the MS got sin2θ and the cos 2θ
thanks!
2. Use this identity

with

then it follows that

3. I've been stuck on this trig question for so long its just

Solve in the 0≤theta≤360

Any help would be really appreciated!
4. use identity

with

to get

See if that is easier to solve!
use identity

with

to get

See if that is easier to solve!
I've tried that.. but i'm stuck again. oh boy.

I honestly don't understand the .
6. No problem.

Ok so we have this

Gonna substitute in for in the original equation

Bring everything over to the LHS

Factorise out

One solution is obtained from here as which implies

Now solve

Bring cos to RHS

Divide by cos and use that to get

This gives degrees

i apologise for spamming this thread.
i wish i was more gifted with numbers
:}

can someone help me with this question?

c) given that (x-2)(x^3 + ax^2 + bx + c)

find values of the constants a b and c

thanks so much!
8. ^Factorise just by long division to find the constants.

And can anyone help me on this one? If sinx = p/q

Write cosec2x in terms of p and q.

9. By writing that as sin(2theta+theta)

show that sin3theta=

lol sorry for the poor latex, I'm still learning to get the hang of it, but anyways can someone please answer this question step by step thank you.
10. ^ For this question you need to apply the sin(A+B) formula but instead with sin(2A+1A) and expand!

Tell me if you get stuck again!
11. (Original post by Apple24)
^ For this question you need to apply the sin(A+B) formula but instead with sin(2A+1A) and expand!

Tell me if you get stuck again!
haha thnx for that i already figured it out, I had to use sin(a+b) and double angle formulae's.
12. Hi,

Does anybody know where I could download EDEXCEL C3 and C4 that was sat in Jan 2010.

Many Thanks

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Updated: February 21, 2010
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