Question:

The line through the points (h, 3) and (4, 1) intersects the line \(7x - 9y - 19 = 0\). at right angle. Find the value of h.

Updated On: Oct 22, 2023
Hide Solution
collegedunia
Verified By Collegedunia

Solution and Explanation

The slope of the line passing through points (h, 3) and (4, 1) is \(m_1 = \frac{(1-3)}{(4-h)} = \frac{-2}{(4-h)}\)
The slope of line  \(7x - 9y - 19 = 0\)  or  \(y = \frac{7}{9}x – \frac{19}{9} \)  is  \(m_2 =\frac{ 7}{9}\)
It is given that the two lines are perpendicular. 
\(∴m_1 × m_2 = -1\)

\(⇒\frac{-2}{(4-h)} \times\frac{ 7}{9} = -1\)

\(⇒\frac{-14}{\left(36-9h\right)} = -1\)
\(⇒-14= -1\times(36 – 9h)\)
\(⇒36 – 9h = 14\)
\(⇒9h = 36 – 14\)
\(⇒h =\frac{ 22}{9}\)
Thus, the value of h is \(\frac{22}{9}.\)

Was this answer helpful?
0
0

Concepts Used:

Straight lines

A straight line is a line having the shortest distance between two points. 

A straight line can be represented as an equation in various forms,  as show in the image below:

 

The following are the many forms of the equation of the line that are presented in straight line-

1. Slope – Point Form

Assume P0(x0, y0) is a fixed point on a non-vertical line L with m as its slope. If P (x, y) is an arbitrary point on L, then the point (x, y) lies on the line with slope m through the fixed point (x0, y0) if and only if its coordinates fulfil the equation below.

y – y0 = m (x – x0)

2. Two – Point Form

Let's look at the line. L crosses between two places. P1(x1, y1) and P2(x2, y2)  are general points on L, while P (x, y) is a general point on L. As a result, the three points P1, P2, and P are collinear, and it becomes

The slope of P2P = The slope of P1P2 , i.e.

\(\frac{y-y_1}{x-x_1} = \frac{y_2-y_1}{x_2-x_1}\)

Hence, the equation becomes:

y - y1 =\( \frac{y_2-y_1}{x_2-x_1} (x-x1)\)

3. Slope-Intercept Form

Assume that a line L with slope m intersects the y-axis at a distance c from the origin, and that the distance c is referred to as the line L's y-intercept. As a result, the coordinates of the spot on the y-axis where the line intersects are (0, c). As a result, the slope of the line L is m, and it passes through a fixed point (0, c). The equation of the line L thus obtained from the slope – point form is given by

y – c =m( x - 0 )

As a result, the point (x, y) on the line with slope m and y-intercept c lies on the line, if and only if

y = m x +c