 Hello and welcome to the session. In this session we discussed the following question which says proves that tan 10 degrees into tan 15 degrees into tan 75 degrees into tan 80 degrees is equal to 1. So let's see the solution. We need to prove that tan 10 degrees into tan 15 degrees into tan 75 degrees into tan 80 degrees is equal to 1. Let us consider the LHS that is tan 10 degrees into tan 15 degrees into tan 75 degrees into tan 80 degrees. Now tan 10 degrees can be written as tan 90 degrees minus 80 degrees into tan 15 degrees can be written as tan 90 degrees minus 75 degrees into tan 75 degrees into tan 80 degrees. We know 90 degrees minus theta is equal to cot theta. Therefore, we get the LHS is further equal to. So now tan 90 degrees minus 80 degrees can be written as cot 80 degrees into tan 90 degrees minus 75 degrees can be written as cot 75 degrees into tan 75 degrees into tan 80 degrees. So this is equal to cot 80 degrees into tan 80 degrees into cot 75 degrees into tan 75 degrees. Now since cot theta multiplied by tan theta is equal to 1. Therefore, this is equal to cot 80 degrees into tan 80 degrees is 1 into cot 75 degrees into tan 75 degrees is 1. So we get the LHS is equal to 1 which is equal to the RHS. Hence we have shown that tan 10 degrees into tan 15 degrees into tan 75 degrees into tan 80 degrees is equal to 1. So this completes the session. Hope you have understood the solution of this question.