Page 161 - ICSE Math 6

¾ Two lines intersecting at an angle of 90° are known as perpendicular lines.

¾ Perpendicular bisector is a line which cuts a given line segment into two equal parts at 90º.
¾ A triangle is a closed figure formed by three line segments which are joined at their end points.
¾ A rectangle is a closed figure formed by four line segments such that the opposite sides are equal
and each angle is of 90°.
¾ A square is a closed figure formed by four line segments such that all the four sides are equal
and each angle is of 90º.
¾ A circle is a set of points in a plane whose distance from a fixed point remain constant.
¾ One and only one line passes through two distinct points in a plane.
¾ Two different lines in a plane are either parallel or intersect at exactly one point.
¾ Three or more points are known as collinear if all of them lie on the same line.
¾ Three or more lines are known as concurrent if all of them pass through the same point.

MENTAL MATHS

1. Fill in the blanks.
(a) A line has only __________ and no __________.

(b) A line segment has __________ end points.
(c) A ray has __________ end point, also known as __________ point.
(d) Two lines in a plane are either __________ or intersect.
(e) A perpendicular bisector divides a line segment into __________ equal parts.

2. Write True or False.

(a) In a rectangle, all sides are equal.
(b) Infinite number of lines can be drawn passing through a point.
(c) Only one line can be drawn passing through two points.
(d) A triangle has four vertices.

3. Which of the following are closed figures?

(a) (b) (c) (d)

PRACTICE TIME

1. How many line segments are there in the following figures?

D
E C
(a) (b) (c)

A B

145