CHAPTER 4

Plotting Polygons (shapes) 

Here we look at polygons plotted on coordinate axes, but first, recall the names of polygons. 

Note: 

In a regular polygon: 

• (a) all the sides are the same. 

• (b) all the angles are of the same size. 

Exercise 

1. In each case the coordinates of 3 corners of a square are given. Find the coordinates of the other corner. (a) (2, -2), (2, 3) and (-3, 3) 

(b) (2, 3), (3, 4) and (1, 4) 

(c ) (2, 2), (4, 4) and (4, 0) 

(d) (-6, 2), (-5, -5) and (1, 3) 

(e) (-5, -2), (-2, -1), and (-1, -4) 

2. The coordinates of 3 corners of a rectangle are given below. Find the coordinates of the other corner of each rectangle. 

(a) (-4, 2), (-4, 1) and (6, 1) 

(b) (0, 2), (-2, 0) and (4, -6) 

(c ) (-4, 5), (-2, -1) and (1, 0) 

(d) (-5, 1), (-2, 5) and (6, -1) 

3. (a) The coordinates of 2 corners of a square are (-4, 4) and (1, -1). Explain why it is possible to draw three different squares using these two points. 

(b) Draw the three different squares. 

(c ) If the coordinates of the corners had been (-5, 1) and (1, 3) would it still be possible to draw 3 squares? Draw the possible squares. 

Use of Appropriate Scale for Given Data 

At times we encounter large values for x and y ,and for such cases we are required to use a convenient scale such that all our values can be able to t on the graph paper.

 EXAMPLE: 

Plot the following points on the axes: A(5, 50), B(10,100), C(15,150), D(20,200), E(25,250) , F(30, 300), G(35,350). you realise that on the horizontal axis(x- values) there are 5 units for each space and On the vertical axis (y- values)there are 50 units for each space 

• Horizontal scale : 1cm:5 

• Vertical axis :1cm :50