Class 10 Ncert Concepts & Questions

Example 1 : If tan A = 4/3, find other Trigonometric Ratios of angle A

This is a typical Class 10 CBSE trigonometry problem. If you’re given tan A = 4/3, the goal is to find the remaining five trigonometric ratios. Let’s solve this step by step using the triangle sides: perpendicular, base, and hypotenuse.

Step-by-Step Solution:

We are given:

  • tan A = 4/3
    That means:
  • Perpendicular = 4 units
  • Base = 3 units

Now, let’s find the hypotenuse using the Pythagoras Theorem:

Hypotenuse² = Perpendicular² + Base²
Hypotenuse² = 4² + 3² = 16 + 9 = 25
Hypotenuse = √25 = 5

So, the triangle has:

  • Perpendicular = 4
  • Base = 3
  • Hypotenuse = 5

All Trigonometric Ratios of ∠A:

  1. sin A = Perpendicular / Hypotenuse = 4 / 5
    2. cos A = Base / Hypotenuse = 3 / 5
    3. tan A = Perpendicular / Base = 4 / 3 (Given)
    4. cot A = Base / Perpendicular = 3 / 4
    5. sec A = Hypotenuse / Base = 5 / 3
    6. cosec A = Hypotenuse / Perpendicular = 5 / 4

Final Answer:

  • sin A = 4/5
  • cos A = 3/5
  • tan A = 4/3
  • cot A = 3/4
  • sec A = 5/3
  • cosec A = 5/4

Why This is Important:

  • Helps solve problems related to heights and distances
  • Shows how all trigonometric ratios connect through a triangle
  • Builds a strong base for advanced math topics in higher classes

Quick Recap:

If tan A = 4/3, draw a triangle where:

  • Perpendicular = 4
  • Base = 3
    Then find the hypotenuse using Pythagoras Theorem and calculate all six trigonometric ratios using the side formulas.

Author: Aman Sir


Aman Sir, the founder of Maths Vidya Institute, has more than 14+ years of experience teaching CBSE Maths to Classes 9–12. His practical explanations help students grasp even the toughest math topics with ease.

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About Er. Aman khanna

Aman Sir, the driving force behind Maths Vidya Institute, is known for his deep understanding of the CBSE Maths curriculum. Since 2009, he has been helping students from Class 9 to 12 score high marks through engaging online sessions, personalized feedback, and consistent performance reviews.
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