Sector Length Cone Area
1. **Problem 1: Find the length $x$ of the sector given the area is 46 cm$^2$.**
The area $A$ of a sector of a circle is given by the formula:
$$A = \frac{\theta}{360} \times \pi r^2$$
where $\theta$ is the central angle in degrees and $r$ is the radius (length $x$ here).
Given:
- $A = 46$ cm$^2$
- $\theta = 80^\circ$
- $\pi \approx 3.14$
Step 1: Substitute the known values:
$$46 = \frac{80}{360} \times 3.14 \times x^2$$
Step 2: Simplify the fraction:
$$\frac{80}{360} = 0.2222$$
Step 3: Rewrite the equation:
$$46 = 0.2222 \times 3.14 \times x^2$$
Step 4: Multiply constants:
$$46 = 0.6977 \times x^2$$
Step 5: Solve for $x^2$:
$$x^2 = \frac{46}{0.6977} \approx 65.95$$
Step 6: Take the square root:
$$x = \sqrt{65.95} \approx 8.1 \text{ cm}$$
2. **Problem 2: Find the area of the card to make a cone-shaped hat with radius 14 cm and slope height 20 cm.**
The surface area $S$ of the cone's lateral side (the card area) is:
$$S = \pi r l$$
where $r$ is the radius and $l$ is the slant height.
Given:
- $r = 14$ cm
- $l = 20$ cm
- $\pi \approx 3.14$
Step 1: Substitute values:
$$S = 3.14 \times 14 \times 20$$
Step 2: Calculate:
$$S = 3.14 \times 280 = 879.2 \text{ cm}^2$$
**Final answers:**
- Length $x$ of the sector: **8.1 cm**
- Area of the card for the cone: **879.2 cm$^2$**