Equation help! (1 Viewer)

Kat92

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Hey guys, just wondering if anyone knows how to solve this equation for R^2 as a little lost as we have just started the yr 12 course and I think that we need to use quadratic equations to solve it the equation is:

12=pi(R^2-1^2)

Any ideas on how I would solve this if I haven't learnt about quadratic equations yet?

Your help would be most appreciated!
 
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kurt.physics

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Kat92 said:
Hey guys, just wondering if anyone know how solve this equation for R^2 as a little lost as we have just started the yr 12 course and I think that we need to use quadratic equations to solve it the equation is:

12=pi(R^2-1^2)

Any ideas on how I would solve this if I haven't learnt about quadratic equations yet?

Your help would be most appreciated!
All we have to do is rearrange the equation so its R2 = ...

So we have

pi(R2 - 12) = 12

We must divide both sides by pi. We get

R2 - 12 = 12/pi

Now we move the - 12 to the other side. Remember it becomes positive

R2 = 12/pi + 12

12 = 1, so

R2 = 12/pi + 1

Now we make the right side a whole fraction

R2 = 12/pi + pi/pi
= (12 + pi)/pi

Now we take the root of both sides to get R

R = root(12 + pi)/root(pi)

This approximately equals 2.195
 

Kat92

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Cheers thanks for your help, it makes much more sense and is very easy to get and apply to other harder questions.
 

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