Find radius..... when area is...... ?

Question

Find radius..... when area is...... ?

Answer 1

need a figure to go on ?

(next time do your own homework)

Answer 2

A = pi x r^2 for area of a flat 2 dimensional circle,

SA = 4/3 x pi x r^2  for surface area of a 3d sphere,

where pi = 3.14 ... r = radius ... A = area ... SA = surface area

To find the radius when given area:

r = sqrt(A/pi)

r = sqrt((4SA)/(3p)i)

where sqrt is the square root sign

Answer 3

Many of the answers given here are incorrect because some people seem to have confused the equations for the volume and the surface area of a sphere. I will first give the answer for a circle (two dimensional) and secondly for a sphere (three dimensional).

circle

A= pi.r.r  or  A=pi.r^2

r=sqrt(A/pi)

=====================================

sphere

A=4.pi.r^2

r=sqrt(A/(4.pi))

but note that for a sphere, volume=(4.pi.r^3)/3 which is what some people used as the equation for the area of a sphere, but this is for the volume, not the surface area.

Hope this helps...

Answer 4

ur ques seems not complete my dear...

anyways,hope u know this--

area of circle=pi*r*r

pi=22/7 or 3.14

e.g if area =36cm^2

36=22/7*r^2

36/3.14=r^2

r^2=11.46

r=3.38cm

Answer 5

... of what?

a circle? a cylinder?

a 3rd degree surface integral?