 Hi and welcome to the session, I am Deepika here. Let's discuss the question, if 3 cot a is equal to 4, check whether 1 minus tan square a upon 1 plus tan square a is equal to cos square a minus tan square a. Now we know that according to the Pythagoras theorem a, b, c right angle at b, a, c square is equal to a, b square plus b, c square equal to a is equal to upon a, c equal to c upon a, b is equal to a, b upon b, c the solution and this is a key idea behind our question. Cot a is equal to 4, a is equal to 4 upon 3 is equal to a descent angle a that is is equal to 4 over 3, therefore is equal to 4, b, c is equal to 3k any positive number. To the Pythagoras theorem that is hypotenuse square is equal to some of the squares of other two sides that is ac square equal to a, b square plus b, c square 4, ac square is equal to 4k square plus 3k square, c square is equal to 16k square plus 9k square, c square is equal to 25k square is equal to, is equal to that is 3k upon 4k which is equal to 3 upon 4 is equal to is equal to 4k upon 5k that is equal to 4 is equal to 3 upon 5 the left hand side is equal to upon 25 therefore our left hand side is equal to 7 upon 25 now on the right hand side we have sine square a by 5 and sine is 3 by 5 this is equal to 3 upon 5 square so this is equal to 25 minus 9 over 25 and this is equal to 7 over 25 equal to right hand side because on both the sides we have 7 over 25 hence the answer for the above question is upon 1 plus sine square a is equal to cos square a minus sine square a when 3k is equal to 4 so I hope the question is clear to you bye and take care