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What we know so far

So far we know these properties of shapes:

Sides! We talk about how many sides the shape has and their lengths.

A square has four sides of equal length.

Corners or Vertices! We talk about how many vertices a shape has.

A square has four vertices

Angles! We talk about the size of the interior angles

The interior angles of a square are 90 degrees.

Symmetry! We talk about how many lines of symmetry a shape has.

A square has four lines of symmetry.

Polygons are 2D shapes that have straight sides that join up. E.g. triangles, hexagons and squares are polygons. Circles are not because they are curved.

Quadrilaterals are 2D shapes that have four sides and four angles that add up to 360 degrees. The rhombus, square and kite are quadrilaterals.

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What are angles?

An angle is the amount of space between two lines that meet each other

This is a right angle.

Right angles = 90 degrees

This is an obtuse angle.

Obtuse angles are between 90 and 180 degrees

This is an acute angle.

Acute angles are less than 90 degrees

A straight line is 180 degrees

This is a reflex angle.

Reflex angles are over 180 degrees

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Name that angle!

This is a ? angle

This is an ? angle

This is a ? angle

This is an ? angle

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The properties of triangles:

Three sides
three vertices (corners)
interior angles that add to 180 degrees

There are three main types of triangle based on the length of the sides:

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Name the triangle!

Two of my sides are the same length. I am a

My angles are 60 degrees. I am a

None of my sides are the same length. I am a

My sides are all equal lengths. I am a

My angles are all different. I am a

Two of my angles are the same. I am a

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Another way to group triangles:

We can also group triangles based on the angles that they have:

We can combine the two names. For example:

I am an acute equilateral triangle.

All of my sides are the same and my angles are all 60 (less than 90)

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Combine the triangle names!

None of my sides are the same length. My largest angle is 90 degrees.