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WEEK FOUR
CLASS: JS TWO
TOPIC: PLANE FIGURES
SUB-TOPICS:
- Construction of areas of regular plane figures
- Construction of Plane figures of equal areas
Content Development (NOTES FOR FIRST LESSON/PERIOD ONE)
Sub-Topic I: Construction of areas of regular plane figures
The area of a plane figure is the space occupied by that figure. Area is usually the product of two lengths and its unit is given in cm2 or m2. The areas of plane figures (also known as polygons) can be obtained through the following methods:
- a) Triangles: The area of a triangle is one-half the product of base and height.
- b) Parallelogram: The area of a parallelogram is the product of one side and the perpendicular distance between that side and the opposite side.
- c) Quadrilateral: A quadrilateral is the combination of two triangles. The areas of the two component triangles are found and added to give the area of the quadrilateral
- d) Square or Rectangle: The area of a square or a rectangle is defined as the product of length and breadth
- e) Trapezium: The area of a trapezium is one-half the product of the sum of parallel sides and the distance between them
- f) Regular polygon: The area of a regular polygon is found by joining the vertices of the polygon to the centre so as to form several triangles. The area of the regular polygon is equal to the area of one of the triangles multiplied by the number of sides.
Evaluation
Discuss the areas of four regular figures
Content Development (NOTES FOR SECOND LESSON/PERIOD TWO)
Sub-Topic II: Construction of Plane figures of equal areas
Construction of a triangle equal in area to a rectangle
Procedure
- draw the rectangle ABCD
- project line CD and mark off DE, using the distant equal to CD
- draw a horizontal line from point F to line BA parallel to BC
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