Everything Maths Grade 10

Step 4: Check that the equation ofCDis in the standard formy=mx+c

2 xy= 2

y= 2x 2

)mCD= 2

Step 5: Write the final answer

mAB=mCD

therefore lineABis parallel to lineCD.

Worked example 7: Perpendicular lines

QUESTION

LineABis perpendicular to lineCD. FindygivenA(2;3),B(2; 6),C(4; 3)andD(7;y).

SOLUTION

Step 1: Draw a sketch

 4  2 2 4 6

 4

 2

2

4

6

A(2;3)

B(2;6)

C(4;3)

D(7;y)

x

y

Step 2: Write down the relationship between the gradients of the perpendicular linesAB?CD

mABmCD= 1

yByA

xBxA



yDyC

xDxC

= 1

Chapter 8. Analytical geometry 301