Answer:
the answer of deviding will be ( -2.1)
The answer is the letter b cos u = 1 /sec u
When you use it in the left side of the identity that you want to verify, sec y cos y = 1 , you get this:
sec y cos y = 1
[sec y ] [ 1 / sec y ] = 1
[sec y] / [sec y] = 1
1 = 1 which proves the idenity.