Ratios and Graphs of Trigonometric Functions
Angle of elevation
The angle measured upward from the horizontal to a line of sight.
| English | Angle of elevation |
|---|---|
| Bahasa Melayu | Sudut dongakan |
| 中文 | 仰角 |
How it is used
A boy 20 m from the foot of a tower looks up at its top with an angle of elevation of 35°. The tower height is 20 × tan 35° ≈ 20 × 0.700 = 14.0 m.
Where it shows up in SPM
Angle of elevation appears in the Trigonometric Ratios chapter of Form 4. It is common in Paper 2 word problems about towers, flagpoles and buildings, where you draw a right-angled triangle and use tangent to find a height or a horizontal distance.
Don't confuse it with
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Frequently asked questions
Where exactly is the angle of elevation drawn?
It is drawn at the observer's eye, between the horizontal line from the eye and the line of sight going up to the object. In a right-angled triangle it sits at the observer's corner, with the height opposite it and the horizontal distance adjacent.
Which ratio should I use for elevation problems?
It depends on which two lengths appear. Height and horizontal distance point to tangent.
Height and slant line of sight point to sine, while horizontal distance and slant line point to cosine. Label the triangle first, then pick the matching ratio.