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How do you calculate the sine, cosine and tangent values for 45 degrees without a calculator?

To find the values for 45 degrees, we construct a right angled isosceles triangle, which has two sides of equal length. We can say that these sides are 1 unit long, and so we can figure out the value of the ...
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Answered by Heather C. • Maths tutor
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Tritium is a radioactive nucleide with a half life of 4500 days, determine the time for 90% of it to decay.

We know that the number of undecayed nuclei, N, is given by N=N 0 e -lambda t . From this, by setting N=N 0 /2 we know at this point that t= T 0.5 (the half life) and can show that lambda =ln(2)/T 0.5 . Henc...
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Answered by Luke C. • Physics tutor
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I decrease a number by 26%, the answer is 9 x10^-7, what was the original number?

The number has been decreased by 26%, this means that the original number is 100-26=74% of the original value. Therefore 9 x 10 -7 = 0.74 x N, where N is the original number. Hence N=(9 x 10 -7 )/0.74 = 1.21...
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Answered by Luke C. • Maths tutor
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How do I integrate the volume of revolution between 0 and pi of y=sin(x)?

To integrate the volume of revolution first imagine a thin disk around the x-axis which we want to know the volume of: Volume=area x height. The area of a circle is given by pi r^2 and in our case let us use...
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Answered by Luke C. • Maths tutor
4389 Views

Solve: x^2-7x+6=0

Factorise the equation and then equate each set of brackets to 0 to obtain both possible solutions. By factorising: (x-6)(x-1)=0 Therefore: x=6 or x=1
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Answered by Phoebe G. • Maths tutor
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