**TERM: 2nd TERM**

**SUBJECT: ****BASIC TECHNOLOGY **** **** **** **** **** **** **

**CLASS: JSS 2**

**REFERENCE MATERIALS **

- MELROSE, Basic Science and Technology, Book 2
- NERDC, Basic Technology for JSS, Book 2

**WEEK TWO **

**TOPIC: QUADRILATERALS **

**CONTENT**

- Types of Quadrilaterals
- Construction of a rectangle given its diagonal and one side
- Construction of a rhombus given its side and a diagonal

- Construction of a rhomboid given its diagonal and one side.

**QUADRILATERALS **

Quadrilaterals are plane figures bounded by four straight lines. The sum of angles in a quadrilateral is 3600.

A straight line called the diagonal may join any two opposite angular points.

**Types of quadrilateral**

- Parallelogram: This is a quadrilateral with it’s opposite sides equal and parallel.
- Square: A square is a parallelogram, which has its entire sides equal and each angle a right angle.
- Rhombus: A rhombus is a parallelogram, which has its sides equal but no angle is a right angle.
- Rectangle: A rectangle is a parallelogram, which has each angle a right angle.
- Rhomboid: A rhomboid is a parallelogram, but no angle is right angled.

**EVALUATION**

- What is a quadrilateral?
- State the types of quadrilateral

**Construction of Squares**

**To construct a square upon a given side.**

(i) Draw a line and mark off AB equal to the side of the square.

(ii) At A, erect a perpendicular AC marking AC equal to AB.

(iii) With center C and a radius equal to AB, strike an arc with center B and the same radius; strike another arc to intersect the previous one at D.

(iv) Joint CD and BD to obtain the required square ABCD

**TO CONSTRUCT A SQUARE GIVEN THE LENGTH OF ITS DIAGONAL.**

*Procedure*

(i) Draw a horizontal line and a vertical line, which intersect at O.

(ii) With center O and a radius equal to half the length of the given diagonal, cut the horizontal line at A and B, and the vertical line at C and D.

(iii) Join AD, DB, BC and CA to obtain the required square ADBC.

*To construct a rectangle given its length and breadth*

(i) Draw a line and mark off AB equal to the length of the rectangle.

(ii) At A, erect a perpendicular AC making AC equal to the breadth of the rectangle.

(iii) With center C and a radius equal to AB, strike an arc. With center B and a radius equal to AC, strike another arc to intersect the previous one at D.

(iv) Join CD and BD to obtain the required rectangle ABDC

**To construct a rectangle given its diagonal and one side.**

*Procedure*

(i) Draw a line and mark off AB equal to the given diagonal.

(ii) Bisect AB at C, and with center C draw a circle with AB as diameter.

(iii) With center A and a radius equal to the given side of the rectangle, cut the circle on any side of AB at D. with center B and the same radius, cut the circle on the other side of AB at E.

(iv) Join AE, EB, BD and DA to obtain the required rectangle AEBD.

**Construction of a Parallelogram**

**To construct a parallelogram given the length of the two sides and one angle**

- Draw one side AB, say 10cm
- Construct the given angle AB1, i.e 120o
- With center B and radius BC, i.e., 4cm, draw an arc to cut B1 at C
- With center A and radius BC, draw an arc
- With center C and radius AB, draw an arc to cut the previous arc at D.
- Join AD and DC

**Construction of a Trapezium**

**To construct a trapezium given the parallel, the perpendicular distance between them and one angle**

- Draw one of the parallels AB=8cm
- Construct the given angle BA1=50o
- Draw the parallel CD, i.e., 4.5cm
- Join D to B to complete the trapezium

**Construction of Rhombus**

**To construct a rhombus given its side and a diagonal.**

**Procedure**

(i) Draw a line and mark off AB equal to the given diagonal.

(ii) With center A and a radius equal to the side, strike arcs above and below AB.

(iii) With center B and the same radius, cut the previous arcs at C and D.

(iv) Join AD, DB, BC and CA to obtain the required rhombus ADBC.

**To construct a rhomboid given a diagonal and two sides.**

**Procedure**

(i) Draw AB equal to the given diagonal.

(ii) With centers A and B and a radius equal to one of the sides, strike arcs above and below AB respectively.

(iii) With center B and a radius equal to the other side, strike arcs to intersect the previous ones at C and D respectively.

(v) Join AD, DB, BC and CA to obtain the required rhomboid ADBC.

**EVALUATION**

- Construct a parallelogram in which length of two sides equal 10cm and one of the angle is 120o
- Construct a square given the length of its diagonal to be 5cm

**READING ASSIGNMENT**

Read about POLYGONS

**REFERENCE MATERIALS**

- MELROSE BASIC SCIENCE AND TECHNOLOGY BOOK 2, page 83-85
- NERDC- BASIC TECHNOLOGY BOOK 2, page 57-61

**WEEKEND ASSIGNMENT**

- A plane figure bounded by four equal sides is called ______ A. square B. rectangle C. trapezium D. kite
- Opposite sides of a parallelogram are _______ A. diagonal B. parallel C. vertex

- straight

- The diagonals in a rhombus bisect each other at A. 900 B. 600 C. 450 D. 700
- A quadrilateral with only two parallel sides is called ____ A. square B. rectangle C. trapezium D. kite
- The diagonals in a trapezium bisect each other to give A. 900 B. equal opposite angles C. parallel opposite angles D. 450

**THEORY **

- Construct (i) a square and (ii) rectangle with diagonal of 120mm
- (i) Define Quadrilateral (ii) Construct a rectangle ABCD, AB=40mm BC=70mm

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