Starter quiz
- An equilateral triangle has __________ equal angles.
- no
- two
- three ✓
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- A rhombus always has __________.
- four angles of equal size
- four angles of different size
- four sides of equal length ✓
- four sides of different length
-
- A rectangle always has __________.
- four angles of equal size ✓
- four angles of different size
- four sides of equal length
- four sides of different length
-
- A square always has __________.
- four angles of equal size ✓
- four angles of different size
- four sides of equal length ✓
- four sides of different length
-
- A square has length 5 cm. Its perimeter is ______ cm.
- '20' ✓
- A rhombus has a base of length 5 cm. Which statement is true about its perimeter?
- Its perimeter is less than 20 cm.
- Its perimeter is equal to 20 cm. ✓
- Its perimeter is more than 20 cm.
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Exit quiz
- A ______ polygon has sides that are all equal and interior (inside) angles that are all equal.
- 'regular' ✓
- An ______ polygon has sides that are not equal or interior (inside) angles that are not equal.
- 'irregular' ✓
- Which quadrilaterals are always regular?
- parallelograms
- rectangles
- rhombi
- squares ✓
- trapezia
-
Why is the octagon in the image not regular?- Not all of its interior angles are the same size.
- Not all of its sides are the same length. ✓
- Both of the above.
-
The perimeter of the heptagon is ______ cm.- '70' ✓
- A circle is __________.
- a regular polygon
- an irregular polygon
- not a polygon ✓
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Worksheet
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Presentation
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Video
Lesson Details
Key learning points
- The prefix is derived from Ancient Greek.
- A regular polygon has sides that are all equal and interior (inside) angles that are all equal.
- An irregular polygon has sides that are not equal or interior (inside) angles that are not equal.
Common misconception
The name for a shape only applies to the regular version of that shape. E.g. An irregular pentagon is just a shape, as pentagons must have 5 equal sides.
The name of a shape is known based on the number of sides and these do not have to be regular.
Keywords
Polygon - A polygon is a flat (2D), closed figure made up of straight line segments.
Regular - A regular polygon has sides that are all equal and interior (inside) angles that are all equal.
Irregular - An irregular polygon has sides that are not equal or interior (inside) angles that are not equal.
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