Points to Remember

Points to Remember

·        An equation involving trigonometric ratios of an angle is called a trigonometric identity if it is true for all values of the angle.

·        Trigonometric identities 

(i) sin ² θ + cos² θ = 1

(ii) 1 + tan ² θ = sec² θ

(iii) 1 + cot² θ = cosec² θ

·        The line of sight is the line drawn from the eye of an observer to the point in the object viewed by the observer.

·        The angle of elevation of an object viewed is the angle formed by the line of sight with the horizontal when it is above the horizontal level.

·        The angle of depression of an object viewed is the angle formed by the line of sight with the horizontal when it is below the horizontal level.

·        The height or length of an object or distance between two distant objects can be determined with the help of trigonometric ratios.