Page 229 - Start Up Mathematics_7

2. Complete the table giving details of line and rotational symmetry for the following letters:

Number Rotational
Line symmetry Order of rotational
Letters of lines of symmetry
Yes/No symmetry
symmetry Yes/No
H
E
C
N
Z
S

3. Which of the following figures have rotational symmetry of order more than 1.

(a) (b) (c) (d) (e) (f)
4. Draw, if possible, a rough sketch of:
(a) a triangle with both line and rotational symmetries of order more than 1.

(b) a triangle with only line symmetry and no rotational symmetry.
(c) a quadrilateral with no line symmetry but rotational symmetry of order more than 1.
(d) a quadrilateral with line symmetry but no rotational symmetry.

(e) a triangle with no line symmetry, but rotational symmetry of order 1.
5. Draw, if possible, a rough sketch of a quadrilateral having lines of symmetry as well as the
order of rotational symmetry equal to:
(a) 1 (b) 2 (c) 4

6. After rotating by 45° about the centre, a figure looks exactly the same as its original position.
At what other angles will the figure look exactly the same? What if the angle is 50° or 60°?
7. Can a figure possessing rotational symmetry have an angle of rotation of measure:
(a) 180° (b) 90° (c) 30° (d) 17° (e) 15° (f) 7°

Fun with Reflection

• Trace the words using the indicated line of symmetry and find the sentence so formed.

• Can you imagine a number whose image remains the same in both horizontal and vertical
line of symmetry? Verify why 8118 is one such number.

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