Page 10 - Cambridge IGCSE Mathematics Core and Extended

Example 2
The diagram is drawn on a grid. Determine the
number of line(s) of symmetry and draw the
line(s) of symmetry of the diagram.

Solution

2 lines of symmetry

B. Completing a symmetrical figure

Example 3
Complete the following shape M
if line MN is the line of
symmetry.

N
Solution
Step  Identify the vertices of the given shape that do not lie
on the line.
Step 2 For each of these vertices, mark the point that has the
same perpendicular distance from the line.
Step 3 Join all the points marked as well as the points lying
on the line to complete the shape.

M M M

N N N
 2 3
C. Rotational symmetry of plane figures

A diagram has rotational symmetry if it still looks the same when rotated. The order of rotational
symmetry is the number of times a diagram looks the same when it is rotated through 360°. There is
a centre of rotation about which the rotational symmetry occurs.
180° 180°

A B C D A B
D C B A D C

150 Cambridge IGCSE Mathematics

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