Line of sight
- CBSE · NCERT Class 10, Ch 9 Some Applications of Trigonometry
The line of sight is the straight line from an observer's eye to the point on the object being looked at.
Height and distance questions start from the observer's eye. Picture a flat line at eye level, called the horizontal. The line of sight goes from the eye to the object. The angle between these two lines is what the question gives you. Looking up, it is an angle of elevation. Looking down, it is an angle of depression.
A small example
A girl's eyes are 1.5 m above the ground. She looks at the top of a pole 11.5 m tall, standing 10 m away. Her line of sight rises 11.5 − 1.5 = 10 m above her eye level. So tan of the angle = 10 ÷ 10 = 1, and the angle is 45°. The triangle starts at her eye, not at her feet.
Where marks go
Question 35 of CBSE's 2026-27 Maths Standard sample paper is a 5-mark heights and distances question. In both versions, the 2026-27 Maths Standard marking scheme gives 1 mark for a correct figure. That mark comes before any calculation.
In version (A), one observer stands on a 50 m building. The scheme gives 1 mark for taking the 50 m away from a height of 100 m. A figure that shows each horizontal line makes this step easy to see. See how step marking splits a long answer.
Sources
Facts last checked against these sources on 30 September 2026.
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