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Find the centre and radius of the circle with the equation x^2 + y^2 - 8x - 6y - 20 = 0.

The general equation of a circle takes the form (x - A)^2 + (y - B)^2 = r^2 where (A,B) is the centre of the circle with radius r. Thus, we aim to rearrange the equation in the question to match this form...

TD
Answered by Thomas D. Maths tutor
7346 Views

Find R and a such that 7*cos(x)+3*sin(x)=Rcos(x-a)

Use the cosine trig identity, cos(a-b)=cos(a)cos(b)+sin(a)sin(b) ,to write Rcos(x-a) as R(cos(x)cos(a)+sin(x)sin(a)).Now we can equate the coefficients of the sines and cosins on either side of the equati...

DY
Answered by Darius Y. Maths tutor
5536 Views

why is the number e important?

When we work with circles, one of the most popular things to pop up is pi. We know that for any circle the circumference divided by the radius gives pi, without failure always. Pi is a number that’s been ...

SV
Answered by Sam V. Maths tutor
2521 Views

Why does the chain rule work?

One of the best ways to view dy/dx is as a fraction. When we have y=f(g(x)), we need to make a substitution u=g(x) to find dy/dx. This leaves us y=f(u) and u=g(x). Differentiating said terms leaves us wit...

SV
Answered by Sam V. Maths tutor
2678 Views

How do we factorise?

The general form of factorising is that if we have ab+ac, we can rewrite this as a(b+c). We multiply each statement inside the bracket by a. So we’re effectively ripping out common terms. We are dividing ...

SV
Answered by Sam V. Maths tutor
2525 Views

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