158k views
1 vote
What is the circumference of a circle with a radius of 2.5 feet

User JF Dion
by
8.3k points

2 Answers

2 votes

\boxed {\boxed {\text{ Circumference of a circle = }2 \pi r}}

Plug in the value of radius = 2.5 into the formula:

Circumference = 2π(2.5) = 15.71 ft (nearest hundredth)


Answer: 15.71 ft
User Carmoreno
by
8.4k points
5 votes
Answer: The circumference of the circle is: " 16 ft. " ;
_________________________________________________________
or; " In term of
\pi , the circumference of the circle is: " 5
\pi ft. " .
_______________________________________________________________

Step-by-step explanation:
_______________________________________________________________
The formula for the circumference, "C" , of a circle:

→ " C = 2 *
\pi * r " ;

→ in which:

" C = circumference of the circle" ;

"r = radius ["length of radius"] = " 2.5 ft " (given) ;


\pi = "3.14" ; which we can use as a commonly accepted
"approximated value" for "
\pi" ;

= "
\pi " ; or, we leave the symbol for "pi" as it is written; if
we are to solve "in terms of pi" ;
____________________________________________________________

Method 1)
To find the circumference, "C", of the circle; in term of "
\pi" :

Note the formula for the circumference, "C", of a circle:

C = 2 *
\pi * r ;

Plug in our given value for the "radius, "r" ; (which is: "2.5 ft.

→ C = 2 *
\pi * (2.5 ft) ;

= 2 * (2.5 ft) *
\pi ;

= 5
\pi ft
.
_________________________________________________________
Answer: In terms of "
\pi" , the circumference of the circle is:

" 5
\pi ft.
"
_________________________________________________________
Method 2) Solve for the circumference of the circle;

→ using "3.14" as an approximation for "
\pi" :
_________________________________________________________

Method 2) [A]:


→ Start by solving for the circumference; "in terms of
\pi" ;
→ {as done above} :

Take the answer, which is: " 5
\pi ft" ;

And solve using "3.14" as an approximation for "
\pi" :

→ " 5 *
\pi " = " 5 * (3.14) = 15.7 ft. ;

→ We can round to: " 16 ft ." ← 2 significant figures.
______________________________________________________

Method 2) [B]: To solve for the circumference of the circle;
→ using "3.14" as an approximation for "
\pi" :

Note the formula for the circumference, "C", of a circle:

C = 2 *
\pi * r ;

Plug in our given value for the "radius, "r" ; (which is: "2.5 ft.") ;

And substitute "3.14" as an "approximation for
\pi" ;
→ in place of the for "
\pi" symbol ;

And rewrite:
____________________________________________________________

→ C = 2 * 3.14 * (2.5 ft) ;

↔ C = 2 * (2.5 ft) * (3.14) ;

= (5 ft) * (3.14) ;

= 15.7 ft. ; we can round to: " 16 ft." (2 signifcant figures).

_____________________________________________________________
User Valya
by
8.5k points

No related questions found

Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.

9.4m questions

12.2m answers

Categories