Trigonometric functions are basically defined for the acute angles of the triangle. We know that the trigonometric functions of an acute angle is the ratio of the pair of sides of the right triangle as per the property. Using the basic trigonometric identities, we can have identities like, angle sum property, triple angle formula, half angle formulae etc. These formulas are helpful in solving any types of triangles for the angles and the side. In real life situations, it is helpful to find the distance and the direction of of ships and the planes from a particular point. In this section let us see some of these identities and the problems based on it.