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# Learn How to Draw Geometric Figures

Sep 15, 2022

### Key Concepts

• Learn to use protector, scale and compass.
• Draw a quadrilateral with given conditions
• Draw a figure to solve a problem
• Draw a figure using technology

## Geometric Shapes:

Geometric shapes can be defined as a figure or area closed by a boundary which is created by combining the specific amount of curves, points, and lines.

The following are the different geometrical shapes.

Some geometrical shapes in real life:

An angle can be defined as the figure formed by two meeting at a common end point.

An angle is represented by the symbol ∠.  Here, the angle below is ∠ABC.

The following illustration represents the different types of angles

## Types of Angles

A quadrilateral is a polygon in Euclidean plane geometry with four edges and four vertices. Other names for quadrilateral include quadrangle and tetragon. A quadrilateral with vertices A, B, C and D.

• Four sides (4 edges)
• Four vertices (4 corners)
• The sum of the interior angles is 360°.

Area: ½ x diagonal x (sum of perpendicular heights)

Perimeter: sum of sides of the quadrilateral

Draw a line segment of length 7.3 cm using a ruler.

Solutions:

Using a ruler, we can draw a line segment of length 7.3 cm as follows

Step 1: Mark a point A on the sheet

Step 2: Place 0 mark of the ruler at point A

Step 3: At 7.3 cm on the ruler, mark a point B on the sheet

Step 4: Now join A and B

Using protractor:

### Constructing Angles Using Protractor – Examples

Example 1:

Construct an acute angle of 60°.

Step 1:

Draw a line segment PA.

Step 2:

1. Place the protractor on the line segment PA
1. Place the midpoint of the protractor at point P, as shown in the figure.

Step 3:

1. On PA from the right, start counting from 0° in the ascending order (counter-clockwise direction) and finally mark a point Q using a sharp pencil at the point showing 60° on the semi-circular edge of the protractor.
1. Remove the protractor and join PQ.
1. We get the required angle ∠APQ  =  60°.

### 8.2.1 Draw Geometric Figures orDraw a quadrilateral with given conditions

1. Construct a line segment of length 5.6 cm using a ruler and a compass.

Solutions:

RS = 5 cm

PS = 4 cm

∠S = 100°

∠R = 120°

For the construction of a quadrilateral with some of the measurements given, we first
draw a rough figure of the quadrilateral with the given dimensions, as shown below.

Now starting with the construction, the steps are:

Step 1: Draw a line segment of length 5 cm and mark the ends as S and R.

Step 2: Using a protractor, draw a line from point R making 120° and another line from point S making 100° with the line segment SR.

Step 3: Set your compass to the radius of 4 cm and make an arc from the point S on the 100° line. Mark the point as P where the arc intersects the line.

Step 4: Similarly, set the compass to the radius of 6 cm and make an arc from point R on the 120° line. Mark the point as Q where the arc intersects the line.

Step 5: Join the points P and Q.

You obtain the quadrilateral PQRS of the required measurements.

To construct an angle using a protractor, we must need the following mathematical instruments.

1. Ruler

2. Protractor

### 8.2.2 Draw a figure to solve a problem

1. Mr Bearl coffee shop has desks shaped like equilateral triangles. He is planning to arrange a desk for 8 people. If two persons can sit at each edge of each desk, then make a sketch to show how many desks he needs.

He will need 6 desks to make the arrangement.

### 8.2.3 Draw a figure using technology

Mr Jason, who works as an architect in an engineering company, is supposed to draw a floor map. His manager gave him the value as follows:

One side of the floor should be 4 cm

The other side of the floor should be 5 cm

Two of the angles should be 600

Solution:

Step 1: Jason draws the first parallel line of 4 cm

Step 2: Jason then draws the first side by measuring 600

Step 3: Jason now duplicates each line segment to create pairs of parallel lines.

Advanced technology such as BIM, VR, and 3D printing is changing the field of architecture, from producing immersive visualization to streamlining communication. Architects are able to draw 3D pictures using computer technology.

## Exercise:

1. If four sides and one diagonal of a quadrilateral are given:

Construct a quadrilateral PQRS where PQ= 5 cm, QR = 7 cm, RS = 6 cm, PS = 6.5 cm and PR = 8 cm.

2. If two diagonals and three sides of a quadrilateral are given:

Construct a quadrilateral ABCD, given that BC = 5.5 cm, AD = 6.5 cm, CD = 5 cm the diagonal AC = 6 cm and diagonal BD = 8 cm

3. If two adjacent sides and three angles of a quadrilateral are given:

Construct a quadrilateral MIST where MI = 3.5 cm, IS = 6.5 cm, ∠M = 75°, ∠I = 105° and ∠S = 120°.

4. Write angles by looking at the pictures:

• Use your protractor to draw these angles:

(i) 40°

(ii) 125°

(iii) 25°

• Circle the alphabets with right angles.
• Fill in the blanks:

(i) A quadrilateral has …………… sides.

(ii) A quadrilateral has …………… angles.

(iii) A quadrilateral has …………… vertices, no three of which are……………… .

(iv) A quadrilateral has …………… diagonals.

(v) A diagonal of a quadrilateral is a line segment that joins two ……………… vertices

(vi) The sum of the angles of a quadrilateral is ……………… .

• The three angles of a quadrilateral are 76°, 54° and 108°. Find the measurement of the fourth angle.
• Draw line segments of the lengths given below:

(1) 5.3 cm         (2) 6.7 cm           (3) 3.8 cm

• Measure and write down the sizes of all the angles and the lengths of all the sides of each quadrilateral below.

Square

## What we have learnt:

• Learn to use protector, scale and compass.
• Draw a quadrilateral with given conditions
• Draw a figure to solve a problem
• Draw a figure using technology

### Concept Map:

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