Example 1 · level 1
If cos A = 4/5 (A acute), find tan A. (answer as a fraction)
Show solution
- Sides: opposite = 3, adjacent = 4, hypotenuse = 5 (opposite = √(5² − 4²) = 3).
- tan A = 3/4.
Answer: 3/4
CLASS 10 MATHS · INTRODUCTION TO TRIGONOMETRY
Find other trigonometric ratios from one
Draw a right triangle with the given ratio, find the third side with Pythagoras, then read off any ratio.
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Worked examples
Example 2 · level 2
If cos A = 4/5 (A acute), find cot A. (answer as a fraction)
Show solution
- Sides: opposite = 3, adjacent = 4, hypotenuse = 5 (opposite = √(5² − 4²) = 3).
- cot A = 4/3.
Answer: 4/3
Example 3 · level 3
If sin A = 8/17 (A acute), find cos A. (answer as a fraction)
Show solution
- Sides: opposite = 8, adjacent = 15, hypotenuse = 17 (adjacent = √(17² − 8²) = 15).
- cos A = 15/17.
Answer: 15/17