cos1°/sin44°-cos89°/sin136°=

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cos1°/sin44°-cos89°/sin136°=cos1°/sin44°-cos89°/sin136°=cos1°/sin44°-cos89°/sin136°=已知sinx=sin(pi-x)

cos1°/sin44°-cos89°/sin136°=
cos1°/sin44°-cos89°/sin136°=

cos1°/sin44°-cos89°/sin136°=
已知sinx=sin(pi-x) cosx=sinx(pi/2-x) sin(x+y)=sinxcosy+cosxsiny
得cos1°=sin89° cos89°=sin1° sin136°=sin44°
则cos1°/sin44°-cos89°/sin136°=sin89°/sin44°-sin1°/sin44°
=(sin89°-sin1°)/sin44°
=(sin(45°+44°)-sin(45°-44°))/sin44°
=√2sin44°/sin44°
=√2