Form 1: Lines and Angles 1

In this chapter, students will be exposed to parallel and perpendicular lines. These two concept of lines are very important in Mathematics. Now let us look how parallel and perpendicular lines are determined.

Parallel Lines

Two straight lines are parallel if:1. They do not meet and intersect one

another.2. They are the same distance apart all along

their lengths.

From the diagram above, we know that,• MN is parallel to OP• WX is parallel to YZ• The perpendicular distance between two

parallel lines XY and YZ is always the same.

Perpendicular Lines

Perpendicular lines are the straight lines that Intersect at a right angle ( 90o). Diagram below can give you better clarification.

C

D

B ALine AB is perpendicular to CD and vice versa.

The concept of parallel line is very important in Vector Chapter in Additional Mathematics. Let’slook at the example below and see how the concept of parallel line is applied in vector. Theexample below is taken from the subtopic of subtracting two vectors.

Example;

In the diagram, 2p . A vector parallel to isgiven as 3p , finda) If and hence, draw the vector . b) if and hence, draw the vector .

2p

Q

P

PQ��������������

MN��������������

2MN PQ RS ������������������������������������������

MN��������������

VW��������������

2 4RS PQ ����������������������������

VW��������������

VW��������������

PQ

RS

a)

b)

p N

M

2MN PQ RS ������������������������������������������

2 4VW RS PQ ������������������������������������������

V

W

-2p

p

pp

pp

2

86

)2(4)3(2

p

pp

322

Point To Be Noted• For the students to answer the vector

question above, they need to have the knowledge about the parallel line concepts. If not they will not be able to draw the line correctly because parallel line has its own characteristics.