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### Trigonometry

1. There are six trigonometrical ratios. Three are fundamental and other three are their reciprocals.
2. The six trigonometrical ratios are
• sine
• cos
• tan
• cosec (reciprocal of sin)
• sec (reciprocal of cos)
• cot (reciprocal of tan)
3. sine: The ratio of perpendicular to hypotenuse is called sine of an angle.
sine α = perpendicular/hypotenuse
sine α = p/h
4. cos: The ratio of base to hypotenuse is called cosine of an angle.
cos α = base/hypotenuse
cos α = b/h
5. tan: The ratio of perpendicular to base is called tangent of an angle.
tan α = perpendicular/base
tan α = p/b
6. cosecant: The ratio of hypotenuse to perpendicular is called cosecant of an angle.
cosec α = hypotenuse/perpendicular
cosec α = h/p
7. secant: The ratio of hypotenuse to base is called secant of an angle.
sec α = hypotenuse/base
sec α = h/b
8. cot: The ratio of base to perpendicular is called cotangent of an angle.
cot α = base/perpendicular
cot α = b/p
9. Trigonometric Tables:
angle\ratiosincostancotseccosec
010/11/010/1
30°1/2√3/21/√3√32/√32
45°1/√21/√211√2√2
60°√3/21/2√31/√322/√3
90°101/00/11/01