Grade: Middle
Subject: Mathematics

#3546. Trigonometry

Mathematics, level: Middle
Posted Thu Sep 8 00:30:32 PDT 2005 by fathuhlla (
feculty of education , male'/ Maldives
Materials Required: Black board and chalk
Concepts Taught: Identify the facts of Right angled Triangle

Subject: Mathematics
Grade: 8
Class: 8c 8
Strength: 30 Students
School: Aminiya
Gender: Girls

Topic: Trigonometry
Sub Topic: Pythagoras theory
Length of time; 70 Minutes
Date: 27th March 2005 (Sunday)
By the end of this lesson all the students will be able to:
 Identify any two facts of the right angled triangle.
 Find the unknown length of right angle triangle, correctly when two sides are given.
 Find the unknown length of a house shaped object correctly when object is given.

Prior Knowledge
Before start of this lesson the students must know:
 Features of the triangles.
 Names of the triangles.
Material required
Black board and chalk
Work Sheet
Hand made triangles.
A house shaped object or house.

Teachers Activities Students Activities Time in minutes
Greeting  Make sure that every one stood up and paying attention to the teacher.
 Greeting to the students' "Good Afternoon."
 Tell the students to sit down.  Students get up.
 Students greeting back "Good afternoon, sir"
 Students getting their chair.

Checking prior knowledge Introduction  Briefly outline or recall the lesson that they learn in grade seven.
 Show them samples of Triangles.
 Ask its features:
 Isosceles triangle
 Scalene triangle
 quadrilateral triangle
 right angled triangle

 Took Right angled Triangle from all the triangles.

 Discuss about its features.
 Explain the names of the sides. Give examples;

 Write two measurements on the Triangle.

 Discuss about the unknown length.

 Students listen to the teacher.
 Responding to the teacher.
 Expected answers:
o Two sides and two angles are equal
o All the angles and sides are different.
o All the sides and angles are equal. Each angle is having 60˚.
o One angle is having 90˚.

 Listen to the teacher.

 Discuss with the teacher.

 Listen to the teacher.
 Respond to the teacher.


 Explain the Pythagoras theory and give brief history of Pythagoras.
 Introduce a formula

 a2 + b2 = c2
 While giving a formula Introduce a Pythagoras triples, i.e.; 3,4,5,6,8,10 and 5, 12, 13.
 Give examples on the board.

 Ask the students how can be calculating the unknown length triangle.
 Explain and workout.
 Give an example
 Select a student and ask to do it on the board.

 Discuss about her answer.
 Ask to copy down.
 Walk around the class.

 Give two questions to do in the class.
 Go around the class and check their work.
 Help those who find it's difficult to do it or not understand.
 Mark some books.
 Discuss about the answers.

 Listen to the teacher.

 Copy down the examples from the board.

 Listen to the teacher.

 Listen to the teacher.

 Helping the teacher to solve the problem
 Expected answer:
By using formula; a2 + b2 = c2
 Listen to teacher.

 A selected student workout and others look her work.

 Copy downs the examples and exercise from the board.

 Copy down the exercise from the board and workout.

 Listen to teacher and discuss with the teacher.




 Spilt the class into 5 groups and take them into the school ground.

 Give the work sheets.

 Explain and give clear instruction about the worksheets.

 Carryout the activity and asks to collect the information.

 Help them.
 Come back to the class.
 Ask to answer to the worksheets using the collected information within the given time.

 Give the answers in group discussion manner.
 Write the correct answer on the board.
 Discuss about the answers.
 Help in making group.

 In a group carry out the work sheet.

 Work out in the group.
 Each group gives its answers.

 Listen and discuss with answers.




 Ask some question :
o What is the special name of the longest side of the right angled triangle?
o What is the formula that used in the Pythagoras theory?

 Greet

 Expected answers:
 Hypotenuse.
 a2 + b2 = c2

 Greet back 5

Pythagoras Theory

1) Do this work in your group.

1) Measure the length of 2b?
2) Measure the length of a?
3) Divide the length of 2b by 2?
4) Find the length of iron sheet that will cover the roof?

2) Tony has got his kite stuck at the top of a very tall tree. He knows the string on his kite is 20 m long. When he pulls the string tight and holds the very end on the ground it touches 17 m from the bottom of the tree. If the ground is flat, how tall is the tree?

3) Robert is using a 5m ladder to climb in his upstairs bedroom window. He finds that if he puts the base of the ladder 3.3m from the wall the top leans on the windowsill. How high from the ground is the windowsill?