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[h] Year 6 Maths Properties of Shapes Study Flashcards

[q] Obtuse, Acute and Right Angles

Angles are measured in degrees °. You can measure angles with a protractor.

[a] A right angle measures 90° and is shown as:

If you turn around fully once, you will have turned through 360°. Because there are four right angles in a whole turn, if you turn 1/4 of a turn you turn 90°.

• Acute angles are less than 90°.

• Obtuse angles are greater than 90° but less than 180°.

• Reflex angles are more than 180° but less than 360°.

So a = b and c = d.

[q] Perpendicular and Parallel Lines

[a] A perpendicular line lies at 90° to another line.

Parallel lines stay the same distance apart and never touch.

[q] Circles

Circles can be described by diameter, radius and circumference:

[a]

d = 2r or r = 1/2 d

[q] Regular and Irregular Shapes

Shapes are regular if their sides are the same length. Irregular shapes have sides of different lengths.

[a]

[q] Triangles and Quadrilaterals

There are three types of triangles:

[a] Equilateral triangles have three equal sides and three equal angles (all 60°).

Isosceles triangles have two equal sides and two equal angles.

Scalene triangles have no equal sides and all their angles are different.

Make sure you know the properties of these quadrilaterals (shapes with four sides):

The interior angles of every triangle always add up to 180° and the interior angles of all quadrilaterals add up to 360°. You can use these known facts to calculate missing angles.

You can calculate the total of the interior angles of any regular polygon by dividing it into triangles.

Example

This pentagon has been divided into three triangles. The angles of a triangle total 180°. So, you can say that the angles of the pentagon = 3 × 180° = 540°

[q] 3-D Shapes

3-D shapes are solid shapes. They are called 3-D because they have three dimensions:

• length

• width

• height.

[a] A 2-D shape only has two dimensions. You need to know which 2-D shapes come together to make up common 3-D shapes.

[q] Nets

A net of a 3-D shape is the 2-D shape that appears if the 3-D shape is opened up.

[a]

You can create nets of common 3-D shapes by putting together 2-D shapes.

[q] Finding Lines of Symmetry

A shape or object is symmetrical if one side is the mirror image of the other.

[a] Example

This plant pot is symmetrical. The dotted line is the line of symmetry. Each side is the mirror image of the other.

Shapes have lines of symmetry:

[q] Completing Symmetrical Patterns

[a]

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