If sec θ + tan θ = x, then tan θ =

Given: sec θ + tan θ = x ……………(i)

To find: tan θ


We know that 1 + tan2 θ = sec2 θ


sec2 θ – tan2 θ = 1


a2 – b2 = (a – b) (a + b)


sec2 θ – tan2 θ = (sec θ – tan θ) (sec θ + tan θ) = 1


From (i), we have


(sec θ – tan θ) x = 1


…………………(ii)


Subtracting (ii) from (i), we get




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