Page 102 - Start Up Mathematics_6

(c) (d)

Perpendicular Lines
Two lines are said to be perpendicular if they intersect at right angles.

Alphabet T Adjacent edges of L.C.D. Adjacent edges of a notebook

Example 16: Which of the following are models of perpendicular lines:
(a) The adjacent edges of a postcard
(b) The lines of a railway track
(c) The line segments forming the symbol of addition ‘+’
(d) The line segments forming the letter X
Solution: (a) The adjacent edges of a postcard and (c) The line segments forming the symbol
of addition ‘+’ are models of perpendicular lines.
Example 17: Study the diagram. Line l is perpendicular to line m.

m

A B C D E F G H
l
0 1 2 3 4 5 6 7 8

(a) Is BE = EH?
(b) Does line m bisect CF?
(c) Identify any two line segments for which line m is the perpendicular bisector.
(d) Are these true?
(i) AD > CE (ii) BC = FG (iii) BC < DG
Solution: (a) Yes, BE = EH
(b) No, line l does not bisect CF.
(c) DF and CG
(d) (i) Yes (ii) Yes (iii) Yes

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