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# Core 3 Question watch

1. Need help with this question. Its on the attachment.
I have done parts i)=PROVE, ii)= (root3)-(root2) and iii)=10.7, 79.3

I can not do part iv). Hope you can help me.

PS. Sorry its a bit small.
Attached Images

2. Use the identity

where

Solve these simultaneously to find the value of A and B, then use this identitiy

You should get the result

So make k - cos(30) outside the range of arcsin, ie k - cos(30) > 1 or k - cos(30) < 1

sorry for rushed responce, gotta go - will check back later!
3. sqrt(3) - 2sin(2x) = k

2sin(2x) = sqrt(3) - k

sin(2x) = [sqrt(3) - k] / 2

2x = arcsin [sqrt(3) - k] / 2

When [sqrt(3) - k] / 2 is greater than 1 or less than -1, the RHS goes tits up and x (or theta) does not exist. Simply write:

[sqrt(3) - k] / 2 > 1

and

[sqrt(3) - k] / 2 < - 1

Solving for k gives:

k < sqrt(3) - 2

or

k > sqrt(3) + 2

Should it not be

N'est-ce pas?
5. Should it not be

Indeed it should - thank you!

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