Question
Find the area $ A $ of a circle if circumference $C = 80\, \text{mm}$.
Answer
$162.1139\pi\, \text{mm}^2$
Explanation
STEP 1: find radius $ r $
To find radius $ r $ use formula:
$$ C = 2 \cdot r \cdot \pi $$After substituting $C = 80\, \text{mm}$ we have:
$$ 80\, \text{mm} = 2 \cdot r \cdot \pi $$ $$ r = \dfrac{ 80\, \text{mm} }{ 2 \pi } $$ $$ r \approx 12.7324\, \text{mm} $$STEP 2: find area $ A $
To find area $ A $ use formula:
$$ A = r^2 \cdot \pi $$After substituting $r = 12.7324\, \text{mm}$ we have:
$$ A = \left( 12.7324\, \text{mm} \right)^{2} \cdot \pi $$ $$ A = 162.1139\, \text{mm}^2 \cdot \pi $$This page was created using
Circle Calculator