SOLUTION:
Two circles have the same center but one circle has a radius 6 cm greater than the other. The area of the inner circle is 221 cm2 less than the outer circle. What is the radius
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Question 1129588:
Two circles have the same center but one circle has a radius 6 cm greater than the other. The area of the inner circle is 221 cm2 less than the outer circle. What is the radius of the smaller circle in centimeters?
Round to 2 decimal place.
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
two circles have the same center, but one circle has a radius 6 cm greater than the other.
The area of the inner circle is 221 cm2 less than the outer circle.
What is the radius of the smaller circle in centimeters?
:
let = the radius of the smaller circle
then
(r+6) = the radius of the larger
:
large area - small area = 221 sq?cm
- = 221
FOIL (r+6)(r+6)
= 221
divide equation by pi
r^2 + 12r + 36 - r^2 = 70.3465
r^2 drops out
12r + 36 = 70.3465
12r = 70.3465 - 36
12r = 34.3465
r =
r = 2.86 cm is the radius of the smaller circle
:
:
:
Check this, find actual area of each (larger radius = 8.86)
= 246.61
= 25.70
-----------------------------
difference in area: 220.9 ~ 221
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