buktikan identitas tersebut

tan α - co α = 1 - 2 cos^2 α /sin α cos α
= 1 - 2 cos^2 α /sin α cos α
= 1/sin α cos α - 2 cos^2 α /sin α cos α
= cos^2 α + sin^2 α /sin α cos α - 2 cos^2 α /sin α cos α
= sin^2 α - cos^2 α/sin α cos α
= sin^2 α /sin α cos α - cos^2 α/sin α cos α
= sin α / cos α - cos α / sin α
= tan α - cotg α
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