In Chapter 9, Class 10 students will learn how to use trigonometry to find the height and distance of objects without measuring them directly. In the past, astronomers relied on trigonometry to calculate distances between planets, Earth, and stars. This chapter explores various ways trigonometry is applied in everyday life.
Topics covered in this chapter include:
By using trigonometric ratios, we can determine the height or length of an object or the distance between two far-away objects.
The horizontal level refers to the straight line that runs through the observer's eye.
The line which is drawn from the eyes of the observer to the point being viewed on the object is known as the line of sight.
ΔABC is a right-angled triangle where the side AB is the vertical side, AC is the longest side (the hypotenuse), and BC is the horizontal side.
The trigonometric ratios are defined as follows:
Trigonometrical Identities:
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Important Definitions & Formulas: Some Applications of Trigonometry
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Q2: When a boy looks from the foot and the top of a tower at the roof of a building, the angles of elevation and depression are 27o and 63o, The height of this building is 40m, then calculate the height of the tower given that tan 630 =2.
Ans: Let the tower be AB
Let the building of height 40m be CD
In the given triangle ACD, AC/DC = cot 270
= cot (90-63)
AC/40 = tan 630 = 2
AC = 80m
Now, DE = AC = 80m
Also, in triangle BED, tan 630 = BE/DE
2= BE/80
Therefore, BE = 160 m
Therefore, the height of the tower can be calculated as AE + EB
= 40 +160 = 200m
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1. What are the key trigonometric ratios used in height and distance problems? | ![]() |
2. How can we calculate the height of a tree using trigonometry? | ![]() |
3. What is the formula to find the distance of an object from a point when the angle of depression is known? | ![]() |
4. What role does the angle of elevation play in solving height and distance problems? | ![]() |
5. Can you explain the relationship between angles of elevation and depression? | ![]() |