1. **State the problem:** We have a rectangle where the length is 5 cm greater than the width. The area of the rectangle is 84 cm². We need to find the length and the width.
2. **Formula used:** The area $A$ of a rectangle is given by:
$$A = \text{length} \times \text{width}$$
3. **Set variables:** Let the width be $w$ cm.
Then the length is $w + 5$ cm.
4. **Write the equation for area:**
$$w \times (w + 5) = 84$$
5. **Expand and simplify:**
$$w^2 + 5w = 84$$
6. **Bring all terms to one side:**
$$w^2 + 5w - 84 = 0$$
7. **Solve the quadratic equation:**
Use the quadratic formula:
$$w = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$
where $a=1$, $b=5$, and $c=-84$.
Calculate the discriminant:
$$\Delta = 5^2 - 4 \times 1 \times (-84) = 25 + 336 = 361$$
Calculate the roots:
$$w = \frac{-5 \pm \sqrt{361}}{2} = \frac{-5 \pm 19}{2}$$
8. **Find possible values for $w$:**
- $w = \frac{-5 + 19}{2} = \frac{14}{2} = 7$
- $w = \frac{-5 - 19}{2} = \frac{-24}{2} = -12$
Since width cannot be negative, $w = 7$ cm.
9. **Find the length:**
$$\text{length} = w + 5 = 7 + 5 = 12 \text{ cm}$$
**Final answer:** The width is 7 cm and the length is 12 cm.
Rectangle Dimensions E00B5A
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