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SubjectFree lesson

Plane figures 2

ClassNotes Team 3 MIN READUPDATED 3 JUL 2026

BASIC SCIENCE JSS2 Second term

Sub-Theme: Drawing practice

WEEK 2 and 3

Plane figures 2

Performance objectives

Students should be able to:

  1. Find the area of regular plane figures.
  2. Enlarge and reduce plane figures.

Content

The area of a regular plane figure

The area of a plane figure is the space occupied by that plane figure. The area is the product of two lengths and its unit is given in cm2. The area of plane figures also known as (polygons) can be obtained through the following methods:

Triangle: the area of a triangle can be one half the product of base and height i.e. area of triangle= ½ base × height

Parallelogram: the area of a Parallelogram is the product on one side and the perpendicular distance between that side and the opposite side.

Area = base × height

Quadrilaterals: this is the combination of two triangles. The areas of the two-component triangles are found and added to give the area of the quadrilateral.

Square or rectangle: the area of a square or rectangle is the product of length and breadth

Trapezium: the area of a trapezium is one half the product of the sum of parallel sides and the distance between them.

A= (a+b/2) h

Regular polygon: the area of a regular polygon is found by joining the vertices of the polygon to the center to form several triangles

Enlargement and reduction of regular plane figures

To construct a figure similar to a given ABCDEF with its sides in the ratio 6.4 to those of the given figure 

  1. Draw the figure ABCDE
  2. Divide the figures into a triangle by drawing lines AC, AD, and AE.

 

  1. Draw line AG at a convenient angle and set off on it from A, 6 equal parts.
  2. Join-point 4 to B and draw GB1 parallel to GB to cut AB produced at B1.
  3. Draw B1, C1, D1, and E1 parallel to BC, CD, and DE respectively to complete the required figure.

Construct a figure similar to a given figure ABCDEF with its sides in the ratio 4:6 to those of the given figure.

  1. Draw the given figure ABCDEF
  2. Divide the figures into triangles by drawing lines AC, AD, and AE.
  3. Divide AB into six equal parts
  4. Draw B1, C1, D1, E1 parallel to CD, BD, and DE respectively to complete the required figure

To construct the size of a given rectangle by a given proportion

  1. Draw the rectangle ABCD
  2. Choose point P at any convenient distance from the rectangle, and radiate lines to corner A, B, C, and D
  3. Divide PA into 6 equal parts.
  4. Draw A1, D1, C1, B1, and A1 respectively to complete the required rectangle.