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JSS2: MATHEMATICS - 3RD TERM

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  1. Scale Drawing | Week 1
    3 Topics
    |
    1 Quiz
  2. Angles of Elevation & Depression | Week 2
    3 Topics
    |
    1 Quiz
  3. Pythagoras’ Theorem I | Week 3
    3 Topics
    |
    1 Quiz
  4. Pythagoras’ Theorem II | Week 4
    2 Topics
    |
    1 Quiz
  5. Area and Volume of Cones and Cylinders | Week 5
    3 Topics
    |
    1 Quiz
  6. Cones | Week 6
    3 Topics
    |
    1 Quiz
  7. Bearings and Distances I | Week 7
    2 Topics
    |
    1 Quiz
  8. Bearings and Distances II | Week 8
    2 Topics
    |
    1 Quiz
  9. Presentation of Data | Week 9
    6 Topics
    |
    1 Quiz
  10. Probability | Week 10
    6 Topics
    |
    1 Quiz



Lesson Progress
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Topic Content:

  • Measuring Angle of Elevation and Depression

Theodolite: Used by surveyors

Theodolite
Theodolite

Clinometer: Made up of a protractor, a tube, and a plumbline attached to the centre of the protractor to indicate the angle. 

Clinometer:
Clinometer

Example 2.3.1: 

From a point, A on a level ground 27.5 cm away from the foot of a tower, the angle of elevation of the top of the tower is observed to be 44°. 

(a) Find by scale drawing, the height of the tower. 
(b) How far is point A from the height of the tower? 

Solution

 Step 1: Start by drawing a rough sketch 

Screenshot 2024 04 22 at 14.19.09

Step 2:   Choose a suitable scale. In this case, 1 cm represents 5 cm. 

|AC| = 27.5 cm, 

Scale = \( \frac{1 \: cm}{5\: cm} \)

27.5 cm becomes

⇒ \( \scriptsize 27.5 \: \times \: \normalsize \frac{1 \: cm}{5 \: cm} \)

= \( \scriptsize 5.5 \: cm \)

Step 3:  Draw a horizontal line of length 5.5 cm and draw the triangle using a protractor, using a 44° angle.

Draw a horizontal line of 5.5 cm

Screenshot 2024 04 22 at 14.25.10

Mark a 44° angle using a protractor

Screenshot 2024 04 22 at 14.27.31

 

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