Shapes Polygons, Symmetry, Nets Hexahedron Tetrahedron

Exterior Angles These are the angles on the outside of the shape They add up to 360° There are 5 sides to a pentagon Therefore each angle is 72°

Interior Angles The angles inside a polygon are called internal angles They always make a straight line with the exterior angle Interior angle + Exterior angle = 180° If the exterior angles are 72° We can work out the internal angles 180 – 72 = 108°

Tessellations This is a pattern made by repeating the same shape over and over again E.g.

Sum of Interior Angles 1.Draw your polygon 2.Join one vertex (corner) to all the others 3.Count the number of triangles 4.Multiply this by 180° 5.Divide this by the number of sides How many triangles are there? 6 6 x 180° = 1,080° How many sides does this shape have? /8 = 135° for each interior angle

Lines of Symmetry A line of symmetry divides a shape into 2 equal parts It can also be called an axis How many lines of symmetry does this shape have? 4

Rotational Symmetry A shape has rotational symmetry if it fits on top of itself more than once as it makes a complete turn The order of rotational symmetry is this number What is the order of rotational symmetry for this shape? 8

Plane of Symmetry This divides a solid (3d) into two equal parts

Net A net is a pattern of shapes that can be folded into a hollow solid These three patterns make the same shape. What is it? A Cube

Nets Most nets have flaps to help you stick the shape together The flaps only need to be on half the sides How many sides does this shape have? 4 This is a tetrahedron

Questions What solids can be made with these nets?

Answers Cylinder Pyramid Tetrahedron