Question:

The equation of a plane containing the line $\frac{x+1}{-3} = \frac{y-3}{2} = \frac{z+2}{1}$ and the point (0,7, - 7) is

Updated On: Aug 15, 2022
  • $x+y + z = 0$
  • $x+ 2y + z=21$
  • $3x-2y + 5z+35 = 0$
  • $3x + 2y + 5z+21 = 0$
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The Correct Option is A

Solution and Explanation

The equation of a plane containing the line $\frac{x+1}{-3} = \frac{y-3}{2} = \frac{z+2}{1}$ is a $(x + 1) + b (y - 3) + c (z + 2) = 0$ where $- 3a + 2b + c = 0 \quad\quad...\left(A\right)$ This passes through $\left(0, 7, - 7\right)$ $\therefore a \left(0 + 1\right) + b \left(7 - 3\right) + c \left(- 7 + 2\right) = 0$ $\Rightarrow a + 4b - 5c = 0 \quad\quad...\left(B\right)$ On solving equation $\left(A\right)$ and $\left(B\right)$ we get $a=1, b=1, c=1$ $\therefore$ Required plane is $x + 1 + y - 3 + z + 2 = 0$ $\Rightarrow x+y + z= 0$
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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