Topic Content:
- Measuring Angle of Elevation and Depression
Theodolite: Used by surveyors
Clinometer: Made up of a protractor, a tube, and a plumbline attached to the centre of the protractor to indicate the angle.
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
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
Mark a 44° angle using a protractor
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