use midpoint equation
radius = distance between midpoint and one of the endpoints.
midpoint: (3+5)/2, (2+6)/2, (5+7)/2 = (4,4,6)
equation of sphere: (x-4)^2 + (y-4)^2 + (z-6)^2 = r^2
square distance between midpoint and one of the endpoints.
r^2 = 6
Equation: (x-4)^2 + (y-4)^2 + (z-6)^2 = 6
Answer:
88/7 ft = 12.6 ft (nearest tenth)
Step-by-step explanation:
Circumference of a circle = 2r
<u>Radius of inner circle</u>
Given:
⇒ 22 = 2 x (22/7) x r
⇒ r = 3.5
So the radius of the inner circle is 3.5 ft
<u>Radius of outer circle</u>
If the distance between the inner circle and the outer circle is 2 ft, then the radius of the outer circle = 3.5 + 2 = 5.5
<u>Circumference of outer circle</u>
Therefore, circumference of outer circle:
= 2 x (22/7) x 5.5
= 242/7 ft
<u>Difference between circumferences</u>
Difference = outer circle circumference - inner circle circumference
= 242/7 - 22
= 88/7 ft
= 12.6 ft (nearest tenth)