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Express 2 cos x – sin x in the form Rcos( x + a ), where R and a are constants, R > 0 and a is between 0 and 90 ° Give the exact value of R and give the value of to 2 decimal places.

2cosx - sinx = Rcos(x+a) = Rcos(x)cos(a)-Rsin(x)sin(a)

Implying

2cos(x)=Rcos(x)cos(a)

Rcosa = 2

Similarly: Rsin(a) = 1

Therefore tan(a) = 1/2

Meaning a=26.57 Degr...

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Answered by Thomas O. Maths tutor
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Mark-recapture is a method of estimating a population size. A sample from the population is captured using an appropriate method, marked, and released. A second sample is then captured after an interval a...

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Given z=cosx+isinx, show cosx=1/2(z+1/z)

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