4 cot2(y)(sec2(y) − 1) = 4

Answer 1

4cot²(y)(sec²(y)-1) = 4

4cot²(y)tan²(y) = 4

4(cos²(y)/sin²(y))(sin²(y)/cos²(y))=4

4(cos²(y)/cos²(y))(sin²(y)/sin²(y))=4

4(1)(1) = 4

4=4