比较大小
(tan33°)^tan56° (tan33°)^tan65° 比较大小 tan138° tan503° tan15° 比较大小 sin5π/7 cos2π/7 tan2π/7 比较大小
1.tan33°,tan56°,tan65°都大于0,0(tan33°)^tan65°2.tan138°=-tan52°0.而tan52°>tan37°,∴-tan52°sin5π/7>cos2π/7,而tan2π/7>1.∴tan2π/7>sin5π/7>cos2π/7
tan33°(tan33°)^tan56° >(tan33°)^tan65 tan138°=-tan42° tan503°=tan(503-360)°=tan143°=-tan37° tan15°>-tan37°>-tan42° ==>tan138°cos2π/7 tan2π/7 =sin(2π/7)/cos(2π/7)> sin(2π/7)=sin5π/7 tan2π/7 >sin5π/7 >cos2π/7
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