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 .