EQUATION OF HORIZONTAL AND VERTICAL LINES

Problem 1 :

Identify as either a vertical or horizontal line and hence plot the graphs of:

a)  y = 3

Solution :

y = b

So, y = 3 is a horizontal line.

b)  x = 4

Solution :

The given line is parallel to y-axis, so it is vertical line passes through 4.

c)  y = -2

Solution :

The given line is parallel to x-axis, so it is horizontal line.

So, y = -2 is a horizontal line.

d)  x = -6

Solution :

The given line is parallel to y-axis. It is in the form of

x = a

So, x = -6 is a vertical line.

Problem 2 :

Identify as either a vertical or horizontal line:

(i)  a line with zero slope   

(ii)  a line with undefined gradient

Solution :

(i) Horizontal line will have zero slope.

(ii)  The vertical lines only will have undefined slope.

Problem 3 :

Find the equation of:

a) The x-axis 

b) The y-axis

c) A line parallel to the x-axis and two units above it

d)  A line parallel to the y-axis and 3 units to the left of it

Solution :

a) The x-axis equation is y = 0

b) The y-axis equation is x = 0

c) The equation of a straight line parallel to the x-axis at a distance of 2 units above the x-axis is y = 2.

d) The equation of the parallel to y-axis at a distance of 3 units to the left is x = -3.

x + 3 = 0