Triangle Area K 650C19
1. **Problem statement:** Find the value of $k$ such that the area of the triangle with vertices $(2, -6)$, $(5, 4)$, and $(k, 4)$ is 35 square units.
2. **Formula for area of triangle given vertices:**
$$\text{Area} = \frac{1}{2} \left| x_1(y_2 - y_3) + x_2(y_3 - y_1) + x_3(y_1 - y_2) \right|$$
3. **Assign vertices:**
$$ (x_1, y_1) = (2, -6), \quad (x_2, y_2) = (5, 4), \quad (x_3, y_3) = (k, 4) $$
4. **Substitute into formula:**
$$\text{Area} = \frac{1}{2} |2(4 - 4) + 5(4 + 6) + k(-6 - 4)|$$
5. **Simplify inside absolute value:**
$$2(0) + 5(10) + k(-10) = 0 + 50 - 10k = 50 - 10k$$
6. **Set area equal to 35:**
$$35 = \frac{1}{2} |50 - 10k| \implies 70 = |50 - 10k|$$
7. **Solve absolute value equation:**
$$50 - 10k = 70 \quad \text{or} \quad 50 - 10k = -70$$
8. **First case:**
$$50 - 10k = 70 \implies -10k = 20 \implies k = -2$$
9. **Second case:**
$$50 - 10k = -70 \implies -10k = -120 \implies k = 12$$
10. **Final answer:**
$$k = -2 \quad \text{or} \quad k = 12$$