The perpendicular from the origin to a line meets it at the point (–2, 9), find the equation of the line.
Solution and Explanation
The slope of the line joining the origin (0, 0) and point (-2, 9) is \(m_1=\frac{9-0}{-2-0}=\frac{-9}{2}\).
Accordingly, the slope of the line perpendicular to the line joining the origin and point (-2, 9) is
\(m_2=\frac{-1}{m_1}=-\frac{1}{\left(-\frac{9}{2}\right)}=\frac{2}{9}\).
Now, the equation of the line passing through point (-2, 9) and having a slope \(m_2\) is
\((y-9)=\frac{2}{9}(x+2)\)
\(9y-81=2x+4\)
\(i.e,2x-9y+85=0\)
Top Questions on Various Forms of the Equation of a Line
- A line passes through (2, 2) and is perpendicular to the line 3x + y = 3. Its y-intercept is
- KCET - 2023
- Mathematics
- Various Forms of the Equation of a Line
- Suppose $ P(2,\,y,\,z) $ lies on the line through $ A(3,-1,4) $ and $ B(-4,2,1) $ . Then, the value of z is equal to
- KCET - 2011
- Mathematics
- Various Forms of the Equation of a Line
- $(0, - 1)$ and $(0, 3)$ are two opposite vertices of a square. The other two vertices are :
- BITSAT - 2006
- Mathematics
- Various Forms of the Equation of a Line
- If lines \(\frac{x-1}{-3}=\frac{y-2}{2k}=\frac{z-3}{2}\) and \(\frac{x-1}{3k}=\frac{y-5}{1}=\frac{z-6}{-5}\) are mutually perpendicular then k is equal to
- KCET
- Mathematics
- Various Forms of the Equation of a Line
- Find the equation of the line passing through the point (2, 2) and cutting off intercepts on the axes whose sum is 9.
- CBSE Class XI
- Mathematics
- Various Forms of the Equation of a Line
Questions Asked in CBSE Class XI exam
- Draw formulas for the first five members of each homologous series beginning with the following compounds.\((a) H–COOH (b) CH_3COCH_3 (c) H–CH=CH_2\)
- CBSE Class XI
- Organic Chemistry- Some Basic Principles and Techniques
- Distinguish between the following pairs of sentences.
(i) He was visibly moved.
(ii) He was visually impaired.- CBSE Class XI
- The adventure
- How, according to you, can peace and liberty be maintained in a state?
- CBSE Class XI
- The tale of melon City
Figures 9.20(a) and (b) refer to the steady flow of a (non-viscous) liquid. Which of the two figures is incorrect ? Why ?
- CBSE Class XI
- Pressure
- Describe the change in hybridisation (if any) of the Al atom in the following reaction.
\(AlCl_3+Cl^- \rightarrow AlCl_4^-\)- CBSE Class XI
- Hybridisation
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