Trigonometric Ratios for 0°, 30°, 45°, 60° angles
What are Trigonometric Ratios?
✓ Ratios of the sides in a right triangle with respect to some acute angles are called trigonometry ratios for specific angles.
✓ The angles 0°, 30°, 45°, 60°, 90° are useful angles in trigonometry.
✓ Trigonometric ratios of angles help in simplifying problems.
Values of Trigonometric Ratios for 0°, 30°, 45°, 60° angles
Find: Cosec230° Sin230° – Sec260°
Putting the values of Cosec 30˚ = 2, sin 30° = 1/2, sec 60° = 2
We get,
= (2)2 x (1/2)2 – (2)2
= (4 x ¼) – 4
= 1 – 4 = -3
Example 2:
Evaluate: 3(cos 30°)2 + (sin 30°)2
We know, cos 30° = √3/2 and sin 30° = 1/2
3(√3/2)2 + (1/2)2
3 x 3 /4 + 1/4
= 9/4 + 1/4
= 10/4
= 5/2
Checkpoint
Problem 1. 2 sin 30° + 2cos 60° – 3 tan 45°
Problem 2. sec245° + cosec3 30° – 3 tan 45°
Problem 3. Solve: sin2 60°+ cos2 (3x – 9) = 1
Answer Key
- -1
- 7
- x = 23
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