Pi()

[Richard]

How would you write the formula for pie squared. My radius is in B2

 

[Dave Peterson]

One way:
=B2*(PI()^2)

But assuming that you really want the area of a circly, then you don't want pi
(not pie) squared.

You want Pi * (Radius squared):
=pi()*(b2^2)
or even
=pi()*b2*b2

Squared means you use the value as a factor twice.

 

[Richard]

One way:
=B2*(PI()^2)

But assuming that you really want the area of a circly, then you don't want pi
(not pie) squared.

You want Pi * (Radius squared):
=pi()*(b2^2)
or even
=pi()*b2*b2

Squared means you use the value as a factor twice.

I'm trying to get the surface area of a circle. pi * radius squared
For example if my circle is 8cm from middle of the part to the end
then my area would be 64. Correct? I can't get 64 for the answer.
Thanks in advance

 

[Dave Peterson]

Nope.

The area of a circle with radius 8cm would be:
=8*8*3.14159
or if b2 contains 8
=b2*b2*pi()
or
=(b2^2)*pi()

Which is a little over 200 sqare cm's.

=========
Just to try to convince you...

If you had a square that was 16cm by 16cm (twice the length of the radius), then
the area would be 16*16=256 square cm's.

And since that circle would fit inside that square, the 201.0619 sq cm seems
reasonable.



On 10/09/2010 15:46, Richard wrote:

 

[Pete_UK]

Think of a square with sides 16cm by 16cm. The area of that would be
16x16 or 256 sq cm. You could just fit your circle of radius 8cm
(diameter 16cm) into that square just touching the sides, and so the
area of the circle will be a bit smaller than the area of the square
(but not a quarter of it - I don't know why you think it should be
64).

The area of the circle is given by Pi times radius squared, i.e Pi x 8
x 8, or Pi x 64 (approx 201 sq cm)

Hope this helps.

Pete

 

[Rick Rothstein]

I'm trying to get the surface area of a circle. pi * radius squared

For example if my circle is 8cm from middle of the part to the end
then my area would be 64. Correct? I can't get 64 for the answer.

If you think the area of a circle with a radius of 8 cm. is 64 sq. cm., then
what do you think the area of a square with sides of 8 cm is?