1. **Problem statement:** Given point $P(-3, y)$ lies on a circle centered at the origin $O$ with radius $OP = 5$ units, and angle $\alpha = \angle XÔP$.
2. **Find $y$:** Use the distance formula for point $P$ from origin $O$:
$$OP = \sqrt{(-3)^2 + y^2} = 5$$
Square both sides:
$$(-3)^2 + y^2 = 5^2$$
$$9 + y^2 = 25$$
Subtract 9:
$$y^2 = 16$$
Take square root:
$$y = \pm 4$$
Since $P$ is above or below x-axis, $y$ can be $4$ or $-4$.
3. **Find $\sin \alpha$:** $\sin \alpha = \frac{\text{opposite}}{\text{hypotenuse}} = \frac{y}{5}$
So,
$$\sin \alpha = \frac{4}{5} \text{ or } \frac{-4}{5}$$
4. **Find $\cos(180^\circ - \alpha)$:** Use the identity:
$$\cos(180^\circ - \alpha) = -\cos \alpha$$
Calculate $\cos \alpha = \frac{x}{5} = \frac{-3}{5}$
So,
$$\cos(180^\circ - \alpha) = -\left(\frac{-3}{5}\right) = \frac{3}{5}$$
5. **Find $\alpha$ (using calculator):**
$$\cos \alpha = \frac{-3}{5} = -0.6$$
So,
$$\alpha = \cos^{-1}(-0.6) = 126.87^\circ$$
6. **Find area of $\triangle POX$ where $X(2,0)$:**
Use formula for area of triangle with vertices $P(-3,4)$, $O(0,0)$, $X(2,0)$:
$$\text{Area} = \frac{1}{2} |x_1(y_2 - y_3) + x_2(y_3 - y_1) + x_3(y_1 - y_2)|$$
Substitute:
$$= \frac{1}{2} |-3(0 - 0) + 0(0 - 4) + 2(4 - 0)|$$
$$= \frac{1}{2} |0 + 0 + 8| = 4$$
**Final answers:**
- $y = \pm 4$
- $\sin \alpha = \pm \frac{4}{5}$
- $\cos(180^\circ - \alpha) = \frac{3}{5}$
- $\alpha = 126.87^\circ$
- Area of $\triangle POX = 4$ units squared
Point P Values Ec46D4
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