CLASS 10 MATHS · INTRODUCTION TO TRIGONOMETRY

Trigonometric ratios of standard angles

Know sin, cos and tan for 0°, 30°, 45°, 60°, 90°. cosec, sec and cot are their reciprocals.

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Worked examples

Example 1 · level 1

What is the value of cos 60°?

1/2
2
√3/2
√2

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cos 60° = 1/2.

Answer: 1/2

Example 2 · level 2

What is the value of tan 45°?

0
1/2
1/√3
1

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tan 45° = 1.

Answer: 1

Example 3 · level 3

Evaluate 4tan²45° + 3cos²45° + 2cos²30°. (answer as a fraction or whole number)

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tan²45° = 1, cos²45° = 1/2, cos²30° = 3/4.
4 × 1 + 3 × 1/2 + 2 × 3/4 = 7.

Answer: 7