# trig

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tan^2theta+6=sec^2theta+5

• trig -

Are we solving for Ø ?

tan^2 Ø +6 = sec^2 Ø + 5
sin^2 Ø/cos^2 Ø + 6 = 1/cos^2 Ø + 5
times cos^2 Ø
sin^2 Ø + 6cos^2 Ø = 1 + 5 cos^2 Ø
sin^2 Ø + cos^2 Ø = 1
1 = 1

ahh, it was an identity, thus true for all values of Ø, except Ø = 90° , 270° , 450° ..... or 90° + 180k , where k is an integer.

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