Angle Of Elevation


Some Applications of Trigonometry - Concepts
Class - RRB Technician Grade I Signal Subjects
 
 
Concept Explanation
 

Angle Of Elevation

Angle of Elevation: An angle of elevation is the angle made by the line of sight to the top of the object and the horizontal line. It is above the horizontal line i.e. the angle of elevation is made when we look up to the object. In the figure below the angle of elevation is the angle between the line of sight and the horizontal level.

 

 

Illustration: The angle of elevation of the top of a tower at the top and the foot of a pole of height 10 m are large 30^{circ} and large 60^{circ} respectively. Find the height of the tower.

SOLUTION: Let AB and CD be the pole and tower respectively.

                 Let CD = h

                Then large angle DAC=60^{circ}  and  large angle DBE=30^{circ}

Now large frac{CD}{CA}=tan;60^{circ}=sqrt{3}therefore CD=sqrt{3}CA;;;Rightarrow frac{h}{sqrt{3}}=CA

Again large frac{DE}{BE}=tan;30^{circ}=frac{1}{sqrt{3}}

large therefore (h-10)=frac{BE}{sqrt{3}}=frac{CA}{sqrt{3}}=frac{h/sqrt{3}}{sqrt{3}};;[because BE=CA]

large Rightarrow 3h-30=hRightarrow 2h=30;;;Rightarrow h=15

Hence, height of the tower = 15 m

Sample Questions
(More Questions for each concept available in Login)
Question : 1

The shadow of an 8 inch long pencil standing vertically on a table is 8sqrt3 inches. The angle of elevation of the top of pencil from the end point of shadow is

Right Option : B
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Explanation
Question : 2

If the lenght of the shadow of a pole is equal to the height of the pole, the angle of elevation of the sun's altitude is

Right Option : C
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Explanation
Question : 3

The lenght of the shadow of a pole is sqrt3 times the height of the pole. The angle of elevation of the sun will be

Right Option : D
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Explanation
 
 


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