Question
Find the side $ a $ of a rectangle if side $b = 20\, \text{cm}$ and perimeter $P = 72\, \text{cm}$.
Answer
$16\, \text{cm}$
Explanation
To find side $ a $ use formula:
$$ P = 2 a + 2 b $$After substituting $P = 72\, \text{cm}$ and $b = 20\, \text{cm}$ we have:
$$ 72\, \text{cm} = 2 a + 2 \cdot 20\, \text{cm} $$ $$ 72\, \text{cm} = 2 a + 40\, \text{cm} $$ $$ 2 a = 72\, \text{cm} - 40\, \text{cm} $$ $$ 2 a = 32\, \text{cm} $$ $$ a = \dfrac{ 32\, \text{cm} }{ 2 } $$ $$ a = 16\, \text{cm} $$This page was created using
Rectangle Calculator