cos5等于多少
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不对,左边等于-1/12,右边等于0
构造直角三角形ABCC=π/2,B=5π/12,A=π/12sinπ/12=sinA=对边/斜边=BC/ABcos5π/12=cosB=邻边/斜边=BC/AB故cos5π/12等于sinπ/12再问:
(1)cos(π/5)+cos(2π/5)+cos(3π/5)+cos(4π/5) =cos(π/5)+cos(2π/5)-cos(2π/5)-cos(π/5) =0(2)tan10°+tan17
2.5m等于25dm=250cm=2500mm再问:打错了,是2.5m等于多少m多少dm?
5分米再答:0.5米=5分米再问:5分米等于多少毫米再答:100再问:谢了再答:不对,是500毫米再问:oo
cos5π/7=cos(π-2π/7)=-cos2π/7tan5π/7=tan(π-2π/7)=-tan2π/7偶函数,f(-x)=f(x)所以f(cos5π/7)=f(cos2π/7)f(tan5π
cos5π/8*cosπ/8=-cos(π-5π/8)*cosπ/8=-cos3π/8*cosπ/8=-cos(π/2-π/8)*cosπ/8=-sin(π/8)*cosπ/8=-sin(π/4)/2
cos²5π/12+cos²π/12+cosπ/12*cos5π/12由于cos5π/12=sin(π/2-5π/12)=sinπ/12原式=sin²π/12+cos
cos^2(π/4+π/6)+cos^2(π/4-π/6)+1/2[cos(5π/12+π/12)+cos(5π/12-π/12)]=cos^2(π/4+π/6)+cos^2(π/4-π/6)+1/2
(4a-5b)(5b-4a)=-(4a-5b)^2=-(16a^2-40ab+25b^2)=-16a^2+40ab-25b^2
cosπ/5×cos2π/5=(2sinπ/5×cosπ/5×cos2π/5)/(2sinπ/5)=(sin2π/5×cos2π/5)/(2sinπ/5)=(2sin2π/5×cos2π/5)/2×(
lg(-2)无意义lg2=0.30102999566398119521373889472449再问:写错了...忘记打根号5了...是lg(-2+根号5)和lg(2+根号5再答:lg(-2+根号5)=
cos5分之πcos10分3π-sin5分之πsin10分之3π=cos(5分之π+10分3π)=cos2分之π=0
五角星1.75、三角形0.5、正方形0.75
多次用倍角公式···可以得到关系关于某个特殊角的多次方···具体自己找找公式···我毕业N久了··公式不记得了···
1,先判断4,5,8,-3在哪个象限,如π〈4〈3/2,在第三象限.2,判断三角函数的符号.如sin4为负号3,判断整个算式的符号.再问:如π〈4〈3/2,在第三象限。??不懂再答:π〈4〈3π/2,
(cos5分之π+cos5分之2π+cos5分之3π+cos5分之4π)=(cos5分之π+cos5分之4π++cos5分之2π+cos5分之3π)=2cos[(5分之π+5分之4π)/2]*cos[
cos5=cos(-5)=cos(2π-5)=sin[π/2-(2π-5)]=sin(5-3π/2)5-3π/2≈0.29则0
只能求正负再问:咋求。。这节课我没听,。。再答:1好像等于37°多吧。忘了。高一学的。然后看图像。再问:哦哦
解题思路:原式=1-1/2+1/2-1/3+……+1/100-1/101=1-1/101=100/101解题过程: