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Express 3cos(theta) + 5sin(theta) in the form Rcos(theta - alpha) where R and alpha are constants, R>0 and 0<alpha<90. Give the exact value of R and the value of alpha to 2dp.

Write out identity: Rcos(theta - alpha) = Rcos(theta)cos(alpha) + Rsin(theta)sin(alpha) from formula booklet Write out in form of question so it's easier to compare: 3cos(theta) + 5sin(theta) = R[cos(alpha)c...
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Answered by Olivia S. • Maths tutor
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how to write down the differential equation from a word problem, involving rate of change.

Read the word problem more than once to make sure you fully understand what is being asked and write down the variables involved. Then try to write down all the derivatives in terms of each other, using the ...
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Differentiate: y = 2 ^ x

y = 2 ^ x take ln of both sides ln( y) = ln (2 ^ x) using the log rules we can bring the power of x down in front of the ln ln( y ) = x*ln(2) differentiate both sides wrt x ( 1 / y ) * dy / dx = ln(2) dy / d...
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Answered by Shantu H. • Maths tutor
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Solve the following simultaneous equations: x^2-y^2=9, x - y = 1

We first notice we have a linear and non linear equation. The simplest method to solve is to substitute the linear equation into the non linear equation and then solve for one of the unknowns. Then substitut...
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Answered by Shantu H. • Maths tutor
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Make s the subject of the equation: 4st + 8 = 5r

To begin this question, we want to isolate the term containing the s, i.e. have the term containing the s by itself on one side of the equality. We do this by subtracting 8 from both sides. 4st = 5r - 8 To m...
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Answered by Sophie W. • Maths tutor
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