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求下列各式的值cos3分之25π=tan(-4分之15π)sin810°+tan765°-cos360°

题目详情
求下列各式的值
cos3分之25π=tan(-4分之15π) sin810°+tan765°-cos360°
▼优质解答
答案和解析
cos(25π/3) = cos(8π+π/3) = cos(π/3) = 1/2 ;
tan(-15π/4) = tan(-4π+π/4) = tan(π/4) = 1 ;
sin810°+tan765°-cos360°
= sin(720°+90°)+tan(720°+45°)-cos0°
= sin(90°)+tan(45°)-1
= 1+1-1
= 1 .