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# Maths C3 question

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1. Hi,

How do you go about expressing equations as a single trigonometrical ratio? How would you do this question for example:

1/2cos(x) - (root3/2)sin(x)

Just to be clear its not the root of 1.5; its root 3 divided by 2.

Thanks a lot
2. bump
3. Use the addition formula, .
4. You use the Rcos(x+alpha) formula? So 1/2cosx -root3/2sinx = cos(x+60)
5. not sure how to solve without intuition
Attached Images

...
"Expand to give...."

Huh? You're not expanding anything. You're applying an identity.
7. That's what I meant sorry. Apply the Cos(A+B) identity to Rcos(x+ alpha)

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Updated: September 13, 2016
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