TgA+ctgA/tgA-ctgA ...

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21 августа, 11:10

TgA+ctgA/tgA-ctgA ...

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Лега · Answer 1

(Sin a/cos a + cos a/sin a) / (Sin a/cos a - cos a/sin a) =

(Sin^2 a+cos^2 a) / (sin a•cos a) : (sin^2 a-cos^2 a) / (sin a•cos a) = (Sin^2 a+cos^2 a) / (sin a•cos a) • (sin a•cos a) /

(Sin^2 - cos^2a) = (sin^2 a+cos^2 a) / (sin^2 a-cos^2 a) =

1 / (-cos 2a) = - 1/cos 2a