 Hello and welcome to the session. Let's work out the following problem. It says prove that secant a into 1- sin a into secant a plus tan a is equal to 1. So let's now move on to the solution. We'll start with NHS and we'll prove that NHS is equal to 1 by simplifying it. NHS is secant a into 1 minus sin a into secant a plus tan a. Secant a can be written as 1 upon cos a into 1 minus sin a. Again secant a is 1 upon cos a plus tan a which is sin a upon cos a and this is equal to 1 upon cos a into 1 minus sin a into taking LCM here. Again we have cos a, LCM will be cos a. So in the numerator we have 1 plus sin, so again this is equal to cos a into cos a is cos square a and in the numerator we have 1 minus sin a into 1 plus sin a upon cos square a. Here we'll be using the formula a minus b into a plus b is equal to a square minus b square and here a is 1 and b is sin a. So this is equal to 1 square that is 1 minus sin square a upon cos square a. And 1 minus sin square a is cos square a upon cos square a. So cos square a upon cos square a is equal to 1, this is RHS. Hence proved. Questions you need to remember the trigonometric identity is very well and by using these identities you can solve these questions very easily. So bye for now, take care, have a good day.