Teach GCSE Maths Lines of Symmetry

Teach GCSE Maths Lines of Symmetry © Christine Crisp "Certain images and/or photos on this presentation are the copyrighted property of JupiterImages and are being used with permission under license. These images and/or photos may not be copied or downloaded without permission from JupiterImages"

These shapes all have at least one line of symmetry. If we could fold a shape along a line of symmetry the two parts would exactly fit.

These shapes all have at least one line of symmetry. If we could fold a shape along a line of symmetry the two parts would exactly fit. Each of these 3 shapes has a special name. Can you tell your partner what they are? Rectangle Isosceles triangle Kite

e.g.1How many lines of symmetry do these shapes have? Parallelogram There are no lines of symmetry We can show a diagonal is not a line of symmetry by reflecting half the parallelogram in the diagonal. The reflected triangle does not match the other half of the parallelogram. Answers: (a) (b) (c) 2 4

e.g.2Complete the diagrams so that the dashed line is a line of symmetry Ans:

1.How many lines of symmetry do these shapes have? EXERCISE Square Rectangle

1.How many lines of symmetry do these shapes have? EXERCISE Square Rectangle 1 4 Ans: The diagonals of a rectangle are not lines of symmetry. 2 2

2.Copy and complete the table for the number of lines of symmetry of the quadrilaterals listed. EXERCISE Kite Other parallelograms Rectangle Rhombus Square Number of lines of symmetry Shape Ans:

SUMMARY  A line of symmetry is like a mirror line.  If we could fold on a line of symmetry the 2 parts would fit together exactly.  A “general” parallelogram has no lines of symmetry. The special ones with equal sides, the square and rhombus, have 4 and 2 lines of symmetry respectively. Square 4 Rhombus 2