Questions: The length of a rectangle is twice its width. If the perimeter of the rectangle is 36 cm, find its area.
Transcript text: The length of a rectangle is twice its width. If the perimeter of the rectangle is 36 cm, find its area.
Solution
Solution Steps
Step 1: Define the variables
Let the width of the rectangle be \( w \) cm. Since the length is twice the width, the length \( l \) is \( 2w \) cm.
Step 2: Write the perimeter formula
The perimeter \( P \) of a rectangle is given by:
\[
P = 2(l + w)
\]
Substitute the given perimeter \( P = 36 \) cm and the expression for \( l \):
\[
36 = 2(2w + w)
\]
Step 3: Solve for the width \( w \)
Simplify the equation:
\[
36 = 2(3w)
\]
\[
36 = 6w
\]
Divide both sides by 6:
\[
w = 6 \text{ cm}
\]
Step 4: Find the length \( l \)
Since \( l = 2w \), substitute \( w = 6 \) cm:
\[
l = 2 \times 6 = 12 \text{ cm}
\]
Step 5: Calculate the area
The area \( A \) of the rectangle is given by:
\[
A = l \times w
\]
Substitute \( l = 12 \) cm and \( w = 6 \) cm:
\[
A = 12 \times 6 = 72 \text{ cm}^2
\]