SOLUTION: Circle has an area of 25 cm2, what is its circumference to the nearest tenth of a centimeter?
I know tha answer is 17.7, but do you just guess at what the radius might be and p
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Question 286443: Circle has an area of 25 cm2, what is its circumference to the nearest tenth of a centimeter?
I know tha answer is 17.7, but do you just guess at what the radius might be and plug it into the pie r2 formula to see what works? I have another the same way on volume of a sphere.
Determine volume of a sphere to nearest cm if surface area is 113 cm2:
Answer is 113 cm3 but again do you just guess at the numbers and plug them into see what works? Never had to do it ths way and my middle grades integrated study guide does not explain.
Found 2 solutions by stanbon, ankor@dixie-net.com:
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Circle has an area of 25 cm^2, what is its circumference to the nearest tenth of a centimeter?
I know tha answer is 17.7, but do you just guess at what the radius might be and plug it into the pie r2 formula to see what works?
------
Area = (pi)r^2 = 25 cm^2
r^2 = (25/pi)
r = 5/sqrt(pi) cm
-----------------------
Circumference = 2(pi)r
C = 2(pi)(5/sqrt(pi))
C = 10(sqrt(pi))
C is approximately 16.48 cm
================================================pi
I have another the same way on volume of a sphere.
Determine volume of a sphere to nearest cm if surface area is 113 cm2:
Answer is 113 cm3 but again do you just guess at the numbers and plug them into see what works? Never had to do it ths way and my middle grades integrated study guide does not explain.
---
Surface area = 4(pi)r^2 = 113 cm^2
r^2 = 113/(4pi)
r = 8.99
r = 2.9987
-----------
Volume = (4/3)pi*r^3
Volume = (4/3)pi(2.9987)^3
Volume is appoximately 112.95 cm^3
=======================================
Cheers,
Stan H.
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
Circle has an area of 25 cm2,
what is its circumference to the nearest tenth of a centimeter?
:
Find r:
= 25
=
r =
Use a calc
r = 2.821
:
Find the circumference
c =
c = 17.72 cm
:
:
Determine volume of a sphere to nearest cm if surface area is 113 cm2:
Find r using the Surface area formula:
= 113
=
Using a calc
r =
r = 2.9987 ~ 3
:
Find volume
v =
v =
v =
using a calc
v = 113.1 cu/cm
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