Question

tg x = 2 calculati ctg( pi/4 - x )

Ajutor !

Answer 1

$ctg\left(\dfrac{\pi}{4}-x\right)=\dfrac{1}{tg\left(\dfrac{\pi}{4}-x\right)}=\dfrac{1}{\dfrac{tg\dfrac{\pi}4-tgx}{1+tg\dfrac{\pi}4\cdot tgx}}=\dfrac{1+tg\dfrac{\pi}4\cdot tgx}{tg\dfrac{\pi}4-tgx}=\\\\\\=\dfrac{1+1\cdot 2}{1-2}=-3.$

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