Answer:
Step-by-step explanation:
The formula for circumference is ...
C = πd
C = (3.14)(4 yd) = 12.56 yd . . . . . . . . fill in the numbers; do the arithmetic
The circumference is 12.56 yd.
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Since the diameter is 4 yd, the radius is half that, or 2 yd. The formula for the area is ...
A = πr²
Fill in the numbers and do the arithmetic.
A = (3.14)(2 yd)² = 12.56 yd²
The area is 12.56 yd².
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Comment on units
In problems such as these, I find it is often useful to keep the units with the numbers. The units can be treated like any variable: multiplied, divided, measures combined by addition or subtraction of "like units".
Just as (2a)² = 2²·a² = 4a², so does (2 yd)² = 2²·yd² = 4 yd². You can be sure that if the units of the problem don't make sense, there is an error somewhere.
