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Ctg de 135 de grade are ce valoare?


Răspuns :



[tex]\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[/tex]


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