The point [tex]\( C \)[/tex] divides the line segment [tex]\( AB \)[/tex] joining the points [tex]\( A(2,3) \)[/tex] and [tex]\( B(-4,1) \)[/tex] in the ratio 2:1. Find the equation of the line passing through the point [tex]\( C \)[/tex] and perpendicular to [tex]\( AB \)[/tex].

[tex]\( र \)[/tex] [tex]$A B$[/tex] सँग लम्ब हुने रेखाको समीकरण निकाल्नुहोस्।
[2070 S]

The point [tex]\( P \)[/tex] divides the line segment [tex]\( AB \)[/tex] in the ratio 2:3. Find the equation of the straight line passing through the point [tex]\( P \)[/tex] and the line [tex]\( 2x + 3y = 6 \)[/tex].



Answer :

To solve this problem, let's go through the process step by step:

1. Find the Coordinates of Point C:
Point [tex]\( C \)[/tex] divides the line segment [tex]\( AB \)[/tex] in the ratio 2:1. We can use the section formula to find the coordinates of [tex]\( C \)[/tex].

Given:
[tex]\( A(2, 3) \)[/tex]
[tex]\( B(-4, 1) \)[/tex]
Ratio [tex]\( = 2:1 \)[/tex]

Using the section formula, the coordinates of [tex]\( C \)[/tex] can be calculated as:
[tex]\[ C \left(\frac{{m x_2 + n x_1}}{{m + n}}, \frac{{m y_2 + n y_1}}{{m + n}} \right) \][/tex]
Here, [tex]\( m = 2 \)[/tex], [tex]\( n = 1 \)[/tex], [tex]\( x_1 = 2 \)[/tex], [tex]\( y_1 = 3 \)[/tex], [tex]\( x_2 = -4 \)[/tex], and [tex]\( y_2 = 1 \)[/tex].

[tex]\[ C_x = \frac{{2 \cdot (-4) + 1 \cdot 2}}{{2 + 1}} = \frac{{-8 + 2}}{{3}} = \frac{{-6}}{{3}} = -2 \][/tex]
[tex]\[ C_y = \frac{{2 \cdot 1 + 1 \cdot 3}}{{2 + 1}} = \frac{{2 + 3}}{{3}} = \frac{{5}}{{3}} \approx 1.6667 \][/tex]

So, the coordinates of point [tex]\( C \)[/tex] are [tex]\( (-2, 1.6667) \)[/tex].

2. Find the Slope of Line AB:
The slope (m) of line segment [tex]\( AB \)[/tex] can be found using the formula:
[tex]\[ m_{AB} = \frac{{y_2 - y_1}}{{x_2 - x_1}} \][/tex]
[tex]\[ m_{AB} = \frac{{1 - 3}}{{-4 - 2}} = \frac{{-2}}{{-6}} = \frac{{1}}{{3}} \][/tex]

So, the slope of [tex]\( AB \)[/tex] is [tex]\( \frac{1}{3} \)[/tex].

3. Find the Slope of the Perpendicular Line:
The slope of a line perpendicular to another line is the negative reciprocal of the original line's slope. So,
[tex]\[ m_{perpendicular} = -\frac{1}{m_{AB}} = -3 \][/tex]

The slope of the line perpendicular to [tex]\( AB \)[/tex] is [tex]\( -3 \)[/tex].

4. Find the Equation of the Perpendicular Line Passing Through Point C:
The equation of a line in slope-intercept form (y = mx + b) can be written as:
[tex]\[ y - y_1 = m(x - x_1) \][/tex]

Here, [tex]\( m = -3 \)[/tex], and the line passes through [tex]\( C(-2, 1.6667) \)[/tex].

Substituting these values:
[tex]\[ y - 1.6667 = -3(x + 2) \][/tex]
[tex]\[ y - 1.6667 = -3x - 6 \][/tex]
[tex]\[ y = -3x - 6 + 1.6667 \][/tex]
[tex]\[ y = -3x - 4.3333 \][/tex]

Hence, the equation of the line that passes through the point [tex]\( C \)[/tex] and is perpendicular to [tex]\( AB \)[/tex] is:

[tex]\[ y = -3x - 4.3333 \][/tex]

This is the required equation.