Everything Maths Grade 11

CHAPTER 16. GEOMETRY 16.5

lating m

m =

y 2 − y 1

x 2 − x 1

=

2 − 1

2 − (−1)

=

1

3

and then substituting this value into
y− y 1 = m(x− x 1 )

to obtain

y− y 1 =

1

3

(x− x 1 ).

Then substitute (−1;1) to obtain

y− (1) =

1

3

(x− (−1))

y− 1 =

1

3

x +

1

3

y =

1

3

x +

1

3

+ 1

y =

1

3

x +

4

3

So, y =^13 x +^43 passes through (−1;1) and (2;2).

1

2

3

3 2 − − 1 − 1 2 3

�

�

(−1;1)

(2;2)

y =^13 x +^43

x

y

Figure 16.2: The equation of the line passing through (−1;1) and (2;2) is y =^13 x +^43.

Example 6: Equation of Straight Line

QUESTION

Find the equation of thestraight line passing through (−3;2) and (5;8).