**FIRST TERM**

**SUBJECT: BASIC TECHNOLOGY**

**CLASS: JSS 2**

**REFERENCE MATERIALS**

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

**WEEK EIGHT**

**TOPIC: TRIANGLES**

**CONTENT**

**Triangles**

**Types of triangles**

**Construction of triangles**

**TRIANGLE**

A triangle is a plane figure bounded by three straight lines and having three angles. The sum of angles in a triangle is 1800

**TYPES OF TRIANGLES **

- Scalene triangle: - This is a triangle that has none of its sides or angles equal.
- Isosceles triangle: - This is a triangle that has two sides and two angles equal.
- Equilateral triangle: - This is a triangle that has all the three sides and angles equal.
- Right-angled triangle: - This is a triangle that one of its angles equal to 900 and the longest line facing the 900 is called
**THE HYPOTENUSE**

**EVALUATION**

- What is a triangle?
- List the types of triangles and describe them.

**TO CONSTRUCT A TRIANGLE GIVEN THE THREE SIDES**

**Procedure**

- Draw the horizontal line and mark off the base of the triangle AB.
- With center A and a radius equal to the length of a side of the triangle, strike an arc
- With center B and a radius equal to the other side strike another arc to cut the previous one at C.
- Join CA and CB to obtain the triangle ABC.

**EVALUATION**

Construct triangle ABC such that AB is 8cm BC 7cm and AC is 6cm

**TO CONSTRUCT A TRIANGLE GIVEN TWO SIDES AND THE INCLUDED ANGLE**

- Draw a horizontal line and mark off one of the given sides AB
- At A, construct the given included angle BAC with the aid of a protractor
- With center A and radius equal to the other given side of the triangle cut AC at D.
- Join DB to complete the required triangle ABD

**EVALUATION**

Construct triangle ABC such that line AB is 5cm,

**TO CONSTRUCT AN EQUILATERAL TRIANGLE USING COMPASSES**

- Draw a horizontal line and mark off base AB equal to the given side.
- With centers A and B and a radius equal to the given side, strike arcs to intersect at C.
- Join CA and CB to obtain the required equilateral triangle.

**EVALUATION**

- Construct an equilateral triangle whose sides are 6cm long.
- Construct triangle ABC such that line AB is 5cm,
0 and line BC is 7cm

**READING ASSIGNMENT**

Read about “CIRCLES”

- MELROSE, Basic Science and Technology, Book 2 page 73-76
- NERDC, BASIC TECHNOLOGY, BOOK 2, page 40- 46

**WEEKEND ASSIGNMENT **

- Which of the following triangles has all its sides equal? (a) Equilateral (b) Scalene (c) Isosceles (d) Right-angled
- Which of the following triangles has none of its side equal? (a) Equilateral (b) Scalene (c) Isosceles (d) Right-angled
- Which of the following triangles has all two sides equal? (a) Equilateral (b) Scalene (c) Isosceles (d) Right-angled
- What is the center rule formula used to construct a polygon as well as dividing a circle into equal parts? (a) 360 – N (b) 360 x N (c) 360/ N (d) 360 + N
- The perpendicular distance from the vertex to the base of triangles is called ______(a) vetoed (b) Aptitude (c) Altitude (d) Interior

**THEORY **

- Construct a rectangle of length 7cm and breadth 5cm with the aid of compass and ruler.
- Construct a square with diagonal 5cm.

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