 Welcome to our session. Let us ask the following question. The question says, the angles of elevation of the top of a tower from two points B and Q at the stances of A and B respectively from the base and in the same straight line with it are complementary. Proof at the height of the tower is square root of A, E. So suppose this is the tower and let height of the tower be given that elevation of the top, suppose this is the point B and this is the point Q, which are at the stances of A and B respectively from the base. That means this distance is A and this is equal to same straight line with it are complementary. That means if this angle is equal to theta, then this angle is equal to 90 minus theta. We have to prove that height of the tower is equal to square root of T B. Now keeping this figure in mind, let's now begin with the solution. Let H that QR is equal to A, which is equal to A and theta. Let us name this as equation number 1. In right triangle is equal to B chord. Let us name this as equation number 2. To B chord into 1 by tan implies H squared is equal to A B and this implies B equal to square root of A B. So we have proved that. So this completes the session by a thank you.