# Lesson Notes By Weeks and Term - Junior Secondary School 2

TERM: 2nd TERM

SUBJECT: BASIC TECHNOLOGY

CLASS:  JSS 2

REFERENCE MATERIALS

1. MELROSE, Basic Science and Technology, Book 2
2. NERDC, Basic Technology for JSS, Book 2

WEEK TWO

CONTENT

• Construction of a rectangle given its diagonal and one side
• Construction of a rhombus given its side and a diagonal
1. Construction of a rhomboid given its diagonal and one side.

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.

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

EVALUATION

2. State the types of quadrilateral

Construction of Squares

1.     To construct a square upon a given side.

#### Procedure

(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

1. 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.

#### Construction of Rectangles

1. To construct a rectangle given its length and breadth

#### Procedure

(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

1. 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

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

Construction of a Trapezium

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

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

Construction of Rhombus

1. 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.

1. 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

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

REFERENCE MATERIALS

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

WEEKEND ASSIGNMENT

1. A plane figure bounded by four equal sides is called ______ A. square B. rectangle C. trapezium D. kite
2. Opposite sides of a parallelogram are _______ A. diagonal B. parallel C. vertex
1. straight
1. The diagonals in a rhombus bisect each other at A. 900 B. 600 C. 450 D. 700
2. A quadrilateral with only two parallel sides is called ____ A. square B. rectangle C. trapezium D. kite
3. The diagonals in a trapezium bisect each other to give A. 900 B. equal opposite angles C. parallel opposite angles D. 450

THEORY

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