Question

Math help please? Please explain because I'm really confused

Answer 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.