1. **Stating the problem:** Given points A(-2,1), B(2,3), and C(-1,-2), find:
a) The equation of the line BC.
b) The area of triangle ABC.
2. **Formula and rules:**
a) The equation of a line through two points $(x_1,y_1)$ and $(x_2,y_2)$ is given by:
$$y - y_1 = \frac{y_2 - y_1}{x_2 - x_1}(x - x_1)$$
b) The area of a triangle with vertices $A(x_1,y_1)$, $B(x_2,y_2)$, and $C(x_3,y_3)$ can be found using the determinant formula:
$$\text{Area} = \frac{1}{2} \left| x_1(y_2 - y_3) + x_2(y_3 - y_1) + x_3(y_1 - y_2) \right|$$
3. **Finding the equation of line BC:**
Points B(2,3) and C(-1,-2)
Slope $m = \frac{y_C - y_B}{x_C - x_B} = \frac{-2 - 3}{-1 - 2} = \frac{-5}{-3} = \frac{5}{3}$
Using point-slope form with point B:
$$y - 3 = \frac{5}{3}(x - 2)$$
Simplify:
$$y - 3 = \frac{5}{3}x - \frac{10}{3}$$
$$y = \frac{5}{3}x - \frac{10}{3} + 3 = \frac{5}{3}x - \frac{10}{3} + \frac{9}{3} = \frac{5}{3}x - \frac{1}{3}$$
Equation of line BC is:
$$y = \frac{5}{3}x - \frac{1}{3}$$
4. **Finding the area of triangle ABC:**
Using the determinant formula:
$$\text{Area} = \frac{1}{2} |(-2)(3 - (-2)) + 2((-2) - 1) + (-1)(1 - 3)|$$
Calculate inside:
$$= \frac{1}{2} |(-2)(5) + 2(-3) + (-1)(-2)| = \frac{1}{2} |-10 - 6 + 2| = \frac{1}{2} |-14| = 7$$
**Final answers:**
a) The equation of line BC is $y = \frac{5}{3}x - \frac{1}{3}$.
b) The area of triangle ABC is 7 square units.
Line Area 2D4059
Step-by-step solutions with LaTeX - clean, fast, and student-friendly.