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Question
Thank you for taking the time to reply to my question. It is:
Simplify this expression using a sum or difference Identity:
sin(x+y)*sec(x)*sec(y)

If you could please include the steps you used to find your answer as well. Thank you.

Answer
Note:  sec (x) = 1/cos(x)   and sec (y) = 1/cos(y).

Also the formula for sum is sin(x+y) = sin(x) cos(y) + cos(x) sin(y)

So if I were to simplify, I will get:

sin(x+y)*sec(x)*sec(y)   =   (sin(x) cos(y) + cos(x) sin(y))/(cos(x) * cos(y) )
         =  (sin(x) cos(y))/(cos(x) * cos(y) ) + (cos(x) sin(y))/(cos(x) * cos(y) )
         =  sin(x)/cos(x)    + sin(y)/cos(y)
         = tan(x) + tan(y)  

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Amos

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I can answer all calculus question. I am a Math Lecturer and I teach Math in a College, usually Calculus 1, Calculus 2 and Calculus 3 and Linear Algebra.

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I have been teaching in this college for more than 12 years. Prior to that, I taught for three years as Visiting Assistant Professor.

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I got my doctorate from Univ. of Rochester in Algebraic Toppology. I got a MA from Univ of Rochester, an MA from York Univ. in Toronto and almost did my M.Sc in the National Univ. of Singapore.

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