Question
Find the side $ b $ of a rectangle if side $a = 12\, \text{cm}$ and perimeter $P = 84\, \text{cm}$.
Answer
$30\, \text{cm}$
Explanation
To find side $ b $ use formula:
$$ P = 2 a + 2 b $$After substituting $P = 84\, \text{cm}$ and $a = 12\, \text{cm}$ we have:
$$ 84\, \text{cm} = 2 \cdot 12\, \text{cm} + 2 b $$ $$ 84\, \text{cm} = 24\, \text{cm} + 2 b $$ $$ 2 b = 84\, \text{cm} - 24\, \text{cm} $$ $$ 2 b = 60\, \text{cm} $$ $$ b = \dfrac{ 60\, \text{cm} }{ 2 } $$ $$ b = 30\, \text{cm} $$This page was created using
Rectangle Calculator