construction of plane shapes

8/7/2019 CONSTRUCTION OF PLANE SHAPES

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S I M P L E I N S T R U M E N T S & M A T E R I A L S

CONSTRUCTING 2-D SHAPES


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ACTIVITY 1: UNDERSTANDINGRELATIONSHIPS BETWEEN 2-D SHAPES

Form groups of 3sList the different types of quadrilaterals that you have

learnt

How are these related? Can you produce a graphic toshow the relationships?


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SPECIAL QUADRILATERALS

A parallelogram has two parallel pairs of opposite sides.

A rectangle has two pairs of opposite sides parallel, and fourright angles. It is also a parallelogram, since it has two pairs ofparallel sides.

A square has two pairs of parallel sides, four right angles, andall four sides are equal. It is also a rectangle and a parallelogram.


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SPECIAL QUADRILATERALS

A rhombus is defined as a parallelogram with four equal sides.Is a rhombus always a rectangle? No, because a rhombus doesnot have to have 4 right angles.

Trapezoids only have one pair of parallel sides. It's a type of

quadrilateral that is not a parallelogram. (Britishname: Trapezium)

Kites have two pairs ofadjacent sides that are equal.


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The Quadrilaterals


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ACTIVITY 2: MEASURABLE PROPERTIES

Discuss the following question What properties of 2-D shapes and 3-D solids can be

measured?


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2-D SHAPES

What are the basic measurable properties of polygons?

Side, perimeter, area andangle.


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3-D SOLIDS

What are the basic measurable properties of 3-D solids?

Side, surface area, volume andangle.


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TO CONSTRUCT A TRIANGLE

Method of construction1. Draw AB, BC and CD equal

in lengtH to the sides ofthe required triangle

2.With centre B and radius ABdraw the arc AF

3.With centre C and radius CDdraw the arc DG

4.Where the arcs at E is anapex of the triangle

5. Join BE and CE with straightlines to form the triangleBCE


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TO CONSTRUCT A SQUARE

Method of construction

1. Mark off one side of the square AB on thebase line

2. With centre A and radius AB draw the arcBC

3. With centre B and radius AB draw the arcAD

4. With centre E and radius AB step off Fand G on arcs BC and ADrespectively

5. With centres E and F draw arcs of equalradius to intersect at H

6. With centres E and G draw arcs of equalradius to intersect at J

7. Erect perpendiculars AH and BJ

8. The arcs BC and AD cut theperpendiculars AH and BJ at K andL respectively

9. To complete the square join K and L


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TO CONSTRUCT A RECTANGLE

Method of construction1. Mark off the lengths of a short sideAB and a long side BC on thebase line

2. Using the constructionsdemonstrated in the previousexamples or using a set square

for simplicity, erectperpendiculars BD and CE at Band C

3. With centre B and radius AB draw anarc to cut BD at F

4. With centre C and radius AB draw anarc to cut CE at G

5. To complete the rectangle join F andG with straight line


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TO CONSTRUCT A PARALLELOGRAM


1. Mark off one short side AB and one longside BC on the base line

2. Draw BD at the required angle ALFA tothe base line using an adjustable setsquare or protractor

3. With centre B and radius AB draw an arcto cut BD at E

4. With centre C and radius AB draw an arc5. With centre E and radius BC draw an arc

to cut the arc drawn in (4) at F

6. To complete the parallelogram join EFand CF with straight lines


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TO CONSTRUCT A PENTAGON


1. With centre O and compasses set torequired radius draw the givencircle

2. Draw a vertical diameter AB and atangent at A

3. With centre A and any suitable radiusdraw a semi-circle

4. With a protractor, divide the semi-circleinto five equal parts (ie. samenumber as sides in the pentagon)and number 0-5

5. From tangent point A draw lines throughthe points 1, 2, 3 and 4 on the semi-circle to cut the given circle at C, D,E and F

6. Complete the pentagon by joining CDEF


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TO CONSTRUCT A HEXAGON


1. Mark off one side AB on the base line

2. Erect perpendiculars AC and BD using one ofthe previously demonstratedconstructions or set square

3. With centre A and radius AB draw an arc to cutthe base line at E

4. With centre E and radius AB draw an arc to cutthe previous arc (3) at G

5. With centre B and radius AB draw an arc to cutthe base line at F

6. With centre F and radius AB draw an arc to cutthe previous arc (5) at H

7. With centre G and radius AB draw an arc to cutthe perpendicular AC at J

8. With centre H and radius AB draw an arc to cutthe perpendicular BD at K

9. To complete the hexagon join AG, GJ, JK, KHand HB with straight lines


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TO CONSTRUCT A OCTAGON


1. Mark off the length of one side AB on the base line

2. Erect perpendiculars AC and BD from A and Brespectively

3. Bisect the angle CAG so that EA lies at 45 degree to GA

4. Similarly, bisect the angle DBH so that BF lies at 45degree to BH

5. With centre A and radius AB draw an arc to cut AE at J

6. With centre B and radius AB draw an arc to cut BF at K

7. Erect perpendiculars at J and K

8. With centres J and K and radius AB draw arcs to cut theperpendiculars at L and M respectively

9. With centres L and M and radius AB draw arcs to cutAC and BD at N and O respectively

10. To complete the octagon join AJ, JL, LN, NO, OM, MKand KB with straight lines


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construction of plane shapes

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