CBSEGrade 11MathematicsTrigonometric Functions

Trigonometric Shadows

A vertical rod of length 10 metres casts a shadow of 8 metres long when the sun's rays make an angle of 60° with the ground. How long will be the shadow when the angle is reduced to 30°?

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📌 CONCEPT: The problem involves finding the length of the shadow when the angle of the sun's rays with the ground changes, related to the trigonometric functions of a right-angled triangle.

📐 RULE / FORMULA: We can use the tangent function to find the length of the shadow, given by tan(angle) = opposite side (shadow) / adjacent side (rod length).

💡 WORKED EXAMPLE: Given the initial angle of 60°, tan(60°) = 8 / 10. We need to find the shadow length when the angle is reduced to 30°. Using the rule tan(angle) = opposite side / adjacent side, we can calculate the new shadow length as tan(30°) = x / 10, where x is the new shadow length. Solving for x, we get x = 10 * tan(30°).

⚠️ COMMON MISTAKE: Students often forget to use the correct trigonometric function (tangent) and the given information (rod length and initial shadow length) to solve the problem.

23 Oct 26