The value of sin A or cos A never exceeds 1, whereas the value of sec A or cosec A is always greater than or equal to 1.
Trigonometric ratios of an acute angle in a right triangle express the relationship between the angle and the length of its sides.
The values of the trigonometric ratios of an angle do not vary with the lengths of the sides of the triangle, if the angle remains the same.
Greek letter θ( theta) is also used to denote an angle
Let’ s see the values of trigonometric ratios for angles 0 °, 30 °, 45 °, 60 ° and 90 °.
From the table above you can observe that as ∠ A increases from 0 ° to 90 °, sin A increases from 0 to 1 and cos A decreases from 1 to 0.
Trigonometric Functions( Any Angle)
In trigonometric ratios, we have studied trigonometric ratios for acute angles as the ratio of sides of a right angled triangle. We will now extend the definition of trigonometric ratios to any angle in terms of radian measure and study them as trigonometric functions.