For example, if you know the circumference of a circle is 25 centimeter (9. 8 in), your formula will look like this: 25=2π(r){\displaystyle 25=2\pi (r)}.
For example:25=2π(r){\displaystyle 25=2\pi (r)}252=2π(r)2{\displaystyle {\frac {25}{2}}={\frac {2\pi (r)}{2}}}12. 5=π(r){\displaystyle 12. 5=\pi (r)}
For example:12. 5=π(r){\displaystyle 12. 5=\pi (r)}12. 5π=π(r)π{\displaystyle {\frac {12. 5}{\pi }}={\frac {\pi (r)}{\pi }}}3. 98=r{\displaystyle 3. 98=r}
For example, if you found the radius to be 3. 98, you would calculate:area=π(r2){\displaystyle {\text{area}}=\pi (r^{2})}area=π(3. 982){\displaystyle {\text{area}}=\pi (3. 98^{2})}area=π(15. 8404){\displaystyle {\text{area}}=\pi (15. 8404)}
For example:area=π(15. 8404){\displaystyle {\text{area}}=\pi (15. 8404)}area=49. 764{\displaystyle {\text{area}}=49. 764}So, the area of a circle with a circumference of 25 centimeter (9. 8 in) is about 49. 764 square centimeters.
For example, if you know the circumference is 25 centimeter (9. 8 in), your formula will look like this: 25=2π(A){\displaystyle 25=2{\sqrt {\pi (A)}}}.
For example:25=2π(A){\displaystyle 25=2{\sqrt {\pi (A)}}}252=2π(A)2{\displaystyle {\frac {25}{2}}={\frac {2{\sqrt {\pi (A)}}}{2}}}12. 5=π(A){\displaystyle 12. 5={\sqrt {\pi (A)}}}
For example:12. 5=π(A){\displaystyle 12. 5={\sqrt {\pi (A)}}}12. 52=(π(A))2{\displaystyle 12. 5^{2}=({\sqrt {\pi (A)}})^{2}}156. 25=π(A){\displaystyle 156. 25=\pi (A)}
For example:156. 25=π(A){\displaystyle 156. 25=\pi (A)}156. 25π=π(A)π{\displaystyle {\frac {156. 25}{\pi }}={\frac {\pi (A)}{\pi }}}49. 7359=A{\displaystyle 49. 7359=A}So, the area of a circle with a circumference of 25 centimeter (9. 8 in) is about 49. 74 square centimeters.
