What is the area of a circle if the diameter is 13 inches?

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Answer 1 · 2018-03-15T13:39:04

See a solution process below:

There relationship between the radius and diameter of a circle is:

#d = 2/r# or #r = d/2#

Therefore, for the circle in this problem the radius is:

#r = (13"in")/2 = 6.5"in"#

The formula for the area of a circle is:

#A = pir^2#

Substituting the radius we solved for above and calculating #A# gives:

#A = pi(6.5"in")^2#

#A = pi42.25"in"^2#

We can approximate #pi# as #3.14# giving:

#A ~= 3.14 * 42.25"in"^2#

#A ~= 132.665"in"^2#