 Hi and welcome to the session. Let us discuss the following question the question says without using trigonometric tables evaluate the following 3 tan 25 tan 40 tan 50 tan 65 minus 1 by 2 into tan square 60 divided by 4 into cos square 29 plus cos square 65. Let us now begin with this illusion. Now here in this question we have to evaluate this expression. Without using trigonometric table this is equal to 3 into now tan 25 can be written as tan 90 minus 65 tan 40 can be written as tan 90 minus 50 into tan 50 into tan 65 minus 1 by 2 tan square 60 is root 3 whole square divided by 4 into now cos square 29 can be written as cos square 90 minus 61 plus cos square 61. T minus 65 is equal to 50 is equal to cos 3 by 2 divided by tan square 61 d 1. Square 61 is also equal to 1.