1. **State the problem:**
We have two functions:
$$f(x) = -\frac{1}{4}x^2$$
$$g(x) = -\frac{2}{3}x$$
Points A and B are the intersections of these graphs. Point C is on the x-axis and is symmetric to B with respect to the y-axis.
We need to:
- Find the coordinates of point B.
- Calculate the area of triangle ABC, rounding the result to one decimal place.
2. **Find the intersection points (A and B):**
Set $f(x) = g(x)$:
$$-\frac{1}{4}x^2 = -\frac{2}{3}x$$
Multiply both sides by 12 (common denominator) to clear fractions:
$$12 \times \left(-\frac{1}{4}x^2\right) = 12 \times \left(-\frac{2}{3}x\right)$$
$$-3x^2 = -8x$$
Bring all terms to one side:
$$-3x^2 + 8x = 0$$
Factor out $x$:
$$x(-3x + 8) = 0$$
So,
$$x = 0 \quad \text{or} \quad -3x + 8 = 0$$
Solve for $x$ in second equation:
$$-3x + 8 = 0 \Rightarrow -3x = -8 \Rightarrow x = \frac{8}{3}$$
3. **Find corresponding y-values:**
For $x=0$:
$$f(0) = -\frac{1}{4} \times 0^2 = 0$$
$$g(0) = -\frac{2}{3} \times 0 = 0$$
So point A is $(0,0)$.
For $x=\frac{8}{3}$:
$$f\left(\frac{8}{3}\right) = -\frac{1}{4} \times \left(\frac{8}{3}\right)^2 = -\frac{1}{4} \times \frac{64}{9} = -\frac{64}{36} = -\frac{16}{9}$$
$$g\left(\frac{8}{3}\right) = -\frac{2}{3} \times \frac{8}{3} = -\frac{16}{9}$$
So point B is $\left(\frac{8}{3}, -\frac{16}{9}\right)$.
4. **Find point C:**
Point C is symmetric to B with respect to the y-axis, so its x-coordinate is the negative of B's x-coordinate, and its y-coordinate is 0 (since it lies on the x-axis):
$$C = \left(-\frac{8}{3}, 0\right)$$
5. **Calculate the area of triangle ABC:**
Vertices:
$$A = (0,0), B = \left(\frac{8}{3}, -\frac{16}{9}\right), C = \left(-\frac{8}{3}, 0\right)$$
Use the formula for area of triangle given coordinates:
$$\text{Area} = \frac{1}{2} \left| x_A(y_B - y_C) + x_B(y_C - y_A) + x_C(y_A - y_B) \right|$$
Substitute values:
$$= \frac{1}{2} \left| 0 \times \left(-\frac{16}{9} - 0\right) + \frac{8}{3} \times (0 - 0) + \left(-\frac{8}{3}\right) \times (0 - \left(-\frac{16}{9}\right)) \right|$$
Simplify terms:
$$= \frac{1}{2} \left| 0 + 0 + \left(-\frac{8}{3}\right) \times \frac{16}{9} \right| = \frac{1}{2} \left| -\frac{128}{27} \right| = \frac{1}{2} \times \frac{128}{27} = \frac{64}{27}$$
6. **Convert to decimal and round:**
$$\frac{64}{27} \approx 2.370370...$$
Rounded to one decimal place:
$$2.4$$
**Final answers:**
- Coordinates of point B: $\left(\frac{8}{3}, -\frac{16}{9}\right)$
- Area of triangle ABC: $2.4$
Intersection Area F2B5D6
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