3.16 Polygons  (Page 2/2)

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DIFFERENCES

between rhombus and square

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17.2 From other groups of three. Follow the same instructions as for 17.1 but build a rectangle instead. If you press on a corner it will change into a parallelogram.

• Now complete the table by comparing the rectangle with the parallelogram:

SIMILARITIES

between rectangle and parallelogram

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DIFFERENCES

between rectangle and parallelogram

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18. What do we call this geometric figure?

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b)

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19. Form groups of four. Your teacher will say who must do a, b, c, and d.

19.1 Discuss the similarities and differences between:

a) a rhombus and a kite;

b) a trapezium and a parallelogram;

c) a rectangle and a trapezium;

d) a kite and a trapezium.

19.2 Make a poster to explain the above and report back to the class.

20. Did you know?

In maths we say a figure / structure is rigid if it can keep its original form even though pressure is applied to one of its corners, e.g.

Not sturdy

Sturdy

20.1 Divide into pairs. Use cool drink straws and build any rigid structure. See if you can build the highest structure in the class!

20.2 TAKE NOTE!

A triangle is the only polygon that is rigid. It doesn’t change its form when pressure is applied to any of its corners.

Where, do you think, do engineers and builders regularly use triangles to ensure stability in their constructions?

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21. Time for self-assessment

Assessment

Learning Outcome 3: The learner will be able to describe and represent characteristics and relationships between two-dimensional shapes and three-dimensional objects in a variety of orientations and positions.

Assessment Standard 3.1: We know this when the learner recognises, visualises and names geometric figures and solids in natural and cultural forms and geometric settings, including those previously dealt with.

Learning Outcome 2: The learner will be able to recognise, describe and represent patterns and relationships, as well as to solve problems using algebraic language and skills.

Assessment Standard 2.3: We know this when the learner represents and uses relationships between variables in order to determine input and/or output values in a variety of ways.