Shaheen2266
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#1
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Hey guys
Can anyone help me with q7 my mind is totally blank


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Sinnoh
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(Original post by Shaheen2266)
Hey guys
Can anyone help me with q7 my mind is totally blank


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The attachment isn't working for me, could you try a different way of uploading it?
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Shaheen2266
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mqb2766
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(Original post by Shaheen2266)
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For the first part, sub angles like x=0, 30, ...
And solve for p,q,r.
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Muttley79
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(Original post by mqb2766)
For the first part, sub angles like x=0, 30, ...
And solve for p,q,r.
The OP was asking about no 7 ... I don't think that's what they are looking for
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16CharsIsTooShor
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Try using the compound angle formulae

hint 1
\cos(A+B)=\cos(A)\cos(B)-\sin(A)\sin(B)

\cos(2A)=\cos^2(A)-\sin^2(A)=2\cos^2(A)-1

hint 2
\cos(3x)=\cos(2x+x)

first few steps
\cos(3x)

= \cos(2x+x)

= \cos(2x)\cos(x)-\sin(2x)\sin(x)

= (2\cos^2(x)-1)\cos(x)-(2\sin(x)\cos(x))\sin(x)
Last edited by 16CharsIsTooShor; 1 month ago
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