Question

The given line passes through the points and (-4, -3) and (4, 1).



What is the equation, in point-slope form, of the line that is perpendicular to the given line and passes through the point (-4, 3)?

Answer 1

Answer:

The equation of the line is y - 3 = -2(x + 4)

Step-by-step explanation:

* Lets explain how to solve the problem

- The slope of the line which passes through the points (x1 , y1) and

  (x2 , y2) is $m=\frac{y_{2}-y_{1}}{x_{2}-x_{1}}$

- The product of the slopes of the perpendicular lines = -1

- That means if the slope of a line is m then the slope of the

  perpendicular line to this line is -1/m

- The point-slope of the equation is $y - y_{1}=m(x - x_{1})$

* lets solve the problem

∵ A given line passes through points (-4 , -3) and (4 , 1)

∴ x1 = -4 , x2 = 4 and y1 = -3 , y2 = 1

∴ The slope of the line $m=\frac{1-(-3)}{4-(-4)}=\frac{1+3}{4+4}=\frac{4}{8}=\frac{1}{2}$

- The slope of the line perpendicular to this line is -1/m

∵ m = 1/2

∴ The slope of the perpendicular line is -2

- Lets find the equation of the line whose slope is -2 and passes

 through point (-4 , 3)

∵ x1 = -4 , y1 = 3

∵ m = -2

∵ y - y1 = m(x - x1)

∴ y - 3 = -2(x - (-4))

∴ y - 3 = -2(x + 4)

* The equation of the line is y - 3 = -2(x + 4)