In which quadrants do cosine and tangent have the opposite sign?

Risposta:

#bb(III)# e #bb(IV)#

Spiegazione:

Starting from the initial side, #theta=0# and rotating counter- clockwise through each quadrant, we have:

#color(white)(888888888)bbIcolor(white)(8888888)bb(II)color(white)(8888888)bb(III)color(white)(8888888)bb(IV)#

#bb(cos(theta)##color(white)(88)bb(+)color(white)(888.88)-color(white)(888.888)-color(white)(8888.88)+#

#bb(tan(theta)##color(white)(88)bb(+)color(white)(888.88)-color(white)(888.888)+color(white)(8888.88)-#

From this we can see that they have opposite signs in quadrants.

#bb(III)# e #bb(IV)#

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