Volume Sphere Radius 2
1. **Stating the problem:** We are given the integral $$\pi \int_{-2}^2 (4 - x^2) \, dx$$ and asked to identify which solid's volume it represents.
2. **Understanding the integral:** The integral $$\int_{-2}^2 (4 - x^2) \, dx$$ represents the area under the curve $$y = 4 - x^2$$ from $$x = -2$$ to $$x = 2$$.
3. **Volume by revolution:** Multiplying this integral by $$\pi$$ suggests the volume of a solid obtained by revolving the curve $$y = 4 - x^2$$ around the x-axis between $$x = -2$$ and $$x = 2$$.
4. **Formula for volume of revolution:** The volume $$V$$ of a solid formed by revolving $$y = f(x)$$ about the x-axis from $$a$$ to $$b$$ is $$V = \pi \int_a^b [f(x)]^2 \, dx$$.
5. **Check the integrand:** Here, the integrand is $$4 - x^2$$, not squared. So the integral $$\pi \int_{-2}^2 (4 - x^2) \, dx$$ is not directly the volume by revolution formula.
6. **Calculate the integral:**
$$\int_{-2}^2 (4 - x^2) \, dx = \left[4x - \frac{x^3}{3}\right]_{-2}^2 = \left(4(2) - \frac{2^3}{3}\right) - \left(4(-2) - \frac{(-2)^3}{3}\right) = \left(8 - \frac{8}{3}\right) - \left(-8 + \frac{-8}{3}\right) = \left(8 - \frac{8}{3}\right) + 8 - \frac{8}{3} = 16 - \frac{16}{3} = \frac{48}{3} - \frac{16}{3} = \frac{32}{3}$$
7. **Multiply by $$\pi$$:**
$$\pi \times \frac{32}{3} = \frac{32\pi}{3}$$
8. **Compare with known volumes:**
- Volume of a sphere: $$\frac{4}{3} \pi r^3$$
- Volume of a right circular cone: $$\frac{1}{3} \pi r^2 h$$
- Volume of a right circular cylinder: $$\pi r^2 h$$
9. **Check each option:**
- (a) Sphere radius 4: $$\frac{4}{3} \pi 4^3 = \frac{4}{3} \pi 64 = \frac{256\pi}{3}$$ (not equal)
- (b) Cone height 4, radius 3: $$\frac{1}{3} \pi 3^2 4 = \frac{1}{3} \pi 9 \times 4 = 12\pi$$ (not equal)
- (c) Sphere radius 2: $$\frac{4}{3} \pi 2^3 = \frac{4}{3} \pi 8 = \frac{32\pi}{3}$$ (matches)
- (d) Cylinder height 4, radius 2: $$\pi 2^2 4 = 16\pi$$ (not equal)
10. **Conclusion:** The volume $$\pi \int_{-2}^2 (4 - x^2) \, dx = \frac{32\pi}{3}$$ matches the volume of a sphere with radius 2 units.
**Final answer:** (c) a sphere whose radius length is 2 units.