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Old November 1st, 2009, 05:34 PM
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Default identity problem
i'm having trouble on this one.

sec^3A-cos^3A/secA-cosA=2+cos^2A+tan^2A

i expand the numerator and eliminate the (secA-cosA) and i get..

sec^2A+secAcosA+cos^2A=2+cos^2A+tan^2A

and then i make secAcosA= to 1 but then i get stuck, could someone help me with this please?
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Old November 1st, 2009, 06:00 PM
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Well,
sec˛A+cosAsecA+cos˛A=1/cos˛+1+cos˛A=(cos˛+sin˛)/cos˛+1+cos˛A=1+sin˛/cos˛+1+cos˛A=2+tan˛A+cos˛A.
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