What is the circumference of a circle that has radius #7"cm"# ?

Question

Mason Adams · Accepted Answer

#7 pi# or #"21.98 cm"# (approx)

#d = "7 cm"# Then #r = d/2 = "3.5 cm"# #c = 2*pi*r # #c = 2 * pi * "3.5 cm" = 7 pi# #"cm"# If you want an exact answer, you can multiply #7# by the value of #pi#, that is # ~~3.14#. So #7 * 3.14 ~~ "21.98 cm"#

Maverick Smith · Answer

The circumference is about #21cm#

The circumference of a circle is about #3# times longer than the diameter.

The actual formula is #C = pi xxD#

The value for #pi# is about #3.142...#

So if you just want an approximate answer, you could say that the circumference of the circle in question is about:

#" "7 xx3 = 21cm#

Allison Allen · Answer

Approximately #22"cm"#. Exactly #7pi"cm"# The ratio between the circumference of a circle and its diameter is #pi#. We commonly write #c = 2pir#, using the radius instead and doubling it. About 1500 years ago, a Chinese mathematician named Zu Chongzhi (祖沖之) calculated #pi# to approximately #7# decimal places and identified two useful rational approximations. One is #22/7#, which is common in use and the other is #355/113 ~~ 3.1415929#, which is less well known but very accurate for the number of digits you have to remember. In the given example, we are told that the diameter is #7"cm"#. So using the common approximation #pi ~~ 22/7#, we find that the circumference is approximately: #22/7 * 7"cm" = 22"cm"#

Sadie Allen · Answer

Circumference = 7#pi#cm

Circumference = #pi# x d Diameter = 7 C = #pi# x 7 C = 7#pi# cm

Mason Adams · Answer

undefined The circumference of a circle is calculated using the formula C = 2πr, where C is the circumference and r is the radius of the circle. In this case, the radius is 7 inches. Therefore, the circumference of the circle is 2π × 7 inches, which is approximately 43.98 inches.