SOLUTION: Prove: sec(alpha + beta)= cos(alpha)cos(beta)+sin(alpha)sin(beta)/cos^2(alpha)-sin^2(beta) I know that sec=1/cos so I changed sec(alpha+beta) to 1/cos(alpha+beta) which gave me:

Question 734294: Prove: sec(alpha + beta)= cos(alpha)cos(beta)+sin(alpha)sin(beta)/cos^2(alpha)-sin^2(beta)
I know that sec=1/cos so I changed sec(alpha+beta) to 1/cos(alpha+beta) which gave me:
a=alpha b=beta
1/cos(a)cos(b)-sin(a)sin(b)
not sure what the next step is. thank you
Answer by lynnlo(4176) (Show Source): You can put this solution on YOUR website!

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