Question

A coordinate map of a college campus gives the coordinates (x,y) of three major buildings as follows: computer center, (3.5,-1.5); engineering lab, (0.5,0.5); andlibrary, (-1,-2.5). Find the equations in slope-intercept form of the lines connecting (a) the engineering lab and the computer center and (b) the engineering lab with the library. Are these two paths perpendicular to each other?

Answer 1

a)
`y = -(2)/(3)x + (5)/(6)`

b)
`y = 2x - (1)/(2)`

These two paths are not perpendicular to each other.

Explanation:

Equation of a line:

The equation of a line has the following format:

`y = mx + b`

In which m is the slope of the line and b is the y-intercept.

If two lines are perpendicular, the multiplication of their slopes is -1.

(a) the engineering lab and the computer center

Coordinates (3.5,-1.5) and (0.5,0.5)

The slope is given by the change in y divided by the change in x.

Change in y: 0.5 - (-1.5) = 0.5 + 1.5 = 2

Change in x: 0.5 - 3.5 = -3

Slope:
`m = (2)/(-3) = -(2)/(3)`

So

`y = -(2)/(3)x + b`

Now, to find the y-intercept, we replace one of these points into the equation.

(0.5,0.5) means that when
`x = 0.5 = (1)/(2), y = 0.5 = (1)/(2)`

So

`y = -(2)/(3)x + b`

`0.5 = -(2)/(3)(0.5) + b`

`b = (1)/(2) + \frac{1}[3}`

`b = (5)/(6)`

So

`y = -(2)/(3)x + (5)/(6)`

(b) the engineering lab with the library.

(0.5,0.5) and (-1,-2.5).

First, we find the slope:

Change in y:-2.5 - 0.5 = -3

Change in x: -1 - 0.5 = -1.5

The slope is:
`m = (-3)/(-1.5) = 2`

So
`y = 2x + b`

Now we find b

`y = 2x + b`

`0.5 = 2(0.5) + b`

`b = -0.5 = -(1)/(2)`

So

`y = 2x - (1)/(2)`

The multiplication of their slopes, is

`2*(-2)/(3) = -(4)/(3)`

Since it is different of one, these paths are not perpendicular to each other.