 I am welcome to the session. Let us discuss the following question. The question says, evaluate integral of cos square x from 0 to pi by 2. Let's now begin with the solution that i is equal to integral of cos square x from 0 to pi by 2. We know that 1 plus cos 2 x divided by 2 is equal to cos square x. This is equal to integral of 1 plus cos 2 x divided by 2 from 0 to pi by 2 is equal to integral of 1 by 2 from 0 to pi by 2 plus 1 by 2 into integral of cos 2 x from 0 to pi by 2. This is equal to 1 by 2 into x lower limit is 0 and upper limit is pi by 2 plus 1 by 2 into sin 2 x lower limit is 0 and upper limit is pi by 2. Now this is equal to 1 by 2 into pi by 2 minus 0. We have substituted the upper limit and then we have substituted the lower limit plus 1 by 2 into sin pi minus sin 0. Now this is equal to pi 2 into pi by 2 plus 1 by 2 into 0 and this is equal to pi by 4. Hence our required answer is pi by 4. So this completes the session. Bye and take care.