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3. Place a set square with one of its edges 4. Slide the set square along the edge of the
along the already aligned edge of the ruler ruler until its right-angled corner coincides
such that the right-angled corner is in with O.
contact with the ruler. 13 12 11 13 12 11

10
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O 8 O
1
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l l
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1 2 3 4 5 6 7 8 9 10 11 12 13
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
cm cm
inches 1 2 3 5 inches 1 2 3 5

5. Hold the set square firmly in this position. Draw OX along the edge of the set square.

Hence,OX ⊥ l.
X
O l
Construction of a Perpendicular to a Line l Through a Point Lying Outside it
Steps of construction:
1. Let us take a line l and a point P outside the line from which a perpendicular is to be drawn
on line l.
P

l
2. Place a set square just below the line l in 3. Place the ruler across the line l in such
such a way that one of the sides containing a way that it touches the side of the set
the right angle touches the line. square opposite the right angle.

P P

l l
A 1 2 3 4 5 6 7 8 9 10 11 12 13 B A 1 2 3 4 5 6 7 8 9 10 11 12 13 cm 15 B
1
1
2 14
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3 13
3
4 12 5
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5 11
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6 10
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7 9
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8 8
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10 10 7 3
13 12 11 13 12 11 5 2 6
3 4
2 1
1
inches
337 Construction of Basic Geometrical Shapes