Question

Ctg de 135 de grade are ce valoare?

Answer 1

$\it ctg135^o=\dfrac{cos135^o}{sin135^o} =\dfrac{-cos(180^o-135^o)}{sin(180^o-135^o)} =\dfrac{-cos45^o}{sin45^o} = \dfrac{-\dfrac{\sqrt2}{2}}{\dfrac{\sqrt2}{2}}=-1$

Answer 2

ctg 135 = ctg (90+45) = ctg90ctg45-1 / ctg90 + ctg 45 = 0-1/ 0+1 = -1