cos0°+cos1°+.cos89°+cos90°等于多少

cos0°+cos1°+.cos89°+cos90°等于多少 求证 1/(COS0°COS1°)+1/(COS1°COS2°)+...+1/(COS88°COS89°)=COS1°/(sin1°)^2裂项法 cos1°/sin44°-cos89°/sin136°= cos1°²+cos2°²+cos3°²+cos4°²...+cos89°²=? Cos1°+cos2°+cos3°+……cos89°= (sin1°-cos1°)(sin2°-cos2°)(sin3°-cos3°)……（sin89°-cos89°）=一定要告诉我原因啊 谢谢最后得0. cos1°的二次方+cos2°的二次方+cos3°的二次方+……cos89°的二次方= cos0°是多少 求cos90+cos89+cos88+……cos0的和 sin90°,sin0°,cos90°,cos0°等于多少? tan30°+sin60°-tan45°+cos0°＝? cos0°+sin270°-tan60°+cos540°=多少? cos0°,tan0°,sin0°的值 cos1°×cos1°+cos2°×cos2°+……+cosn cos1°+cos2°+cos3°.+co180°=? cos1°+cos2°+cos3°+.+cos360° cos1°+cos2°+cos3°+...+cos179°化简 cos1°+cos2°+cos3°+.+cos359°等于多少.