11. The length of a rectangle is 4 centimeters less than twice its width. The perimeter of the rectangle is 34 cm. What are the dimensions of the rectangle?
length 7 cm; width = 10 cm
length 9 cm; width = 8 cm
о
length 14 cm; width = 9 cm
length 10 cm; width = 7 cm



Answer :

To solve this problem, we need to follow these steps:

1. Understand the given relationships:
- The length (L) of the rectangle is 4 centimeters less than twice its width (W).
- The perimeter (P) of the rectangle is 34 cm.

2. Express the length in terms of the width using the given relationship:
[tex]\[ \text{Length} = 2 \times \text{Width} - 4 \][/tex]
So,
[tex]\[ L = 2W - 4 \][/tex]

3. Use the formula for the perimeter of a rectangle, which is:
[tex]\[ P = 2 \times (\text{Length} + \text{Width}) \][/tex]
Given that the perimeter is 34 cm, we can set up the equation:
[tex]\[ 34 = 2 \times (L + W) \][/tex]

4. Substitute the expression for L from step 2 into the perimeter equation:
[tex]\[ 34 = 2 \times ((2W - 4) + W) \][/tex]

5. Simplify and solve for width (W):
[tex]\[ 34 = 2 \times (3W - 4) \][/tex]
[tex]\[ 34 = 6W - 8 \][/tex]
[tex]\[ 42 = 6W \][/tex]
[tex]\[ W = 7 \][/tex]

6. Once we have the width (W), we can find the length (L) using the relationship from step 2:
[tex]\[ L = 2W - 4 \][/tex]
[tex]\[ L = 2 \times 7 - 4 \][/tex]
[tex]\[ L = 14 - 4 \][/tex]
[tex]\[ L = 10 \][/tex]

Therefore, the dimensions of the rectangle are:
- Length: 10 cm
- Width: 7 cm

Among the provided options, the correct one is:
- Length: 10 cm, Width: 7 cm

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