Finding the radius. I haev never understood pi, and would like some explanation. Thanks!

Question

blurbendy · Answer

Pi is basically this:

If you grab a can of soup and some rope, and take the rope and surround the bottom of the can with the rope so that you end up with a circle when you lift the can up, pi is the length around the rope.  Make sense?

anonymous · Answer

Yeah I know that part. I had a picture I want to upload with a question, but for some reason it wouldn't let me even get to my question till now.

anonymous · Answer

@hba

blurbendy · Answer

Work out the area of circle that has a radius of 7cm, giving your answer in terms of Pi.

All you need to do is substitute r = 7 into A = πr²

A = πr²

= π × 7²

Since 7² = 49 (since 7 × 7 = 49) then you have:

= π × 49.

= 49π

So the final answer is 49π cm² (put the number before Pi)

blurbendy · Answer

the circumference of a circle is found by multiplying the diameter to π: C = dπ

if the radius is 7 yards, then the diameter is 14 yards (diameter is twice the radius)

so circumference is C = 14π yards.

anonymous · Answer

Ok thanks so much! I have never fully understood pi for some reason.

blurbendy · Answer

No problem.  It's a weird concept.  Took me a while too.

anonymous · Answer

:)

hba · Answer

I am sorry,I guess i am late :/

anonymous · Answer

:P haha just a wee bit...

hba · Answer

You can actually use buffon's needle to calculate pi.

$$\huge\ \pi \approx\frac{ 2l.n }{ th }  $$

We found out the best approximation 

Which is,

355/113.


We can also use infinite series .

hba · Answer

We use,

$$\huge\ \pi=\frac{ C }{ d } $$

Which is a general way.

anonymous · Answer

Ok. Well honestly I don't know what some of the stuff is... 
Thanks though!