cosπ加x

宓湛庭1765已知COS(π/4+X)=3/5求SIN2X的值
蔺凭汤13128259807 ______ 解:cos(π/4+x)=3/5 cosπ/4cosx-sinπ/4sinx=3/5 √2/2(cosx-sinx)=3/5 (cosx-sinx)=3√2/5 平方得:(cosx)^2+(sinx)^2-2sinxcosx=18/25 1-18/25=2sinxcosx sin2x=7/25

宓湛庭1765cos(π+x)²+cos(π - x) 怎么计算? -
蔺凭汤13128259807 ______ cos(π+x)²+cos(π-x)=cos^2x-cosx

宓湛庭1765已知sin[(π/4) - x)]=5/13,0<x<π/4.求cos2x/(cosπ/4+x) -
蔺凭汤13128259807 ______ 1.∵sin[(π/4)-x)]=5/13,0<x<π/4 ∴cos[(π/4)-x)]=12/13 cos2x=cos[(π/2)-2x]=2sin[(π/4)-x)]*cos[(π/4)-x)]=2*5/13*12/13=120/169 cos[(π/4)+x]=sin[π/2-(π/4+x)]=sin(π/4-x)=5/13 ∴cos2x/cos[(π/4)+x]=120/169 /5/13 =24/132.∵0<β<π/2<α<π 又∵cos[α-(β/2)]=-1...

宓湛庭1765已知cos(π/4 +x)=3/5,17π/12<x<7π/4,求(sin2x+2sin??x)/1 - tanx的值 -
蔺凭汤13128259807 ______ 您好:解答如下17π/12

宓湛庭1765cos四分之派+x 怎么变成 sin四分之派 - x -
蔺凭汤13128259807 ______ cos四分之派+x=sin[pai\2-(四分之派+x)]=sin四分之派-x

宓湛庭1765cos(π/4+x)=3/5,17π/12<x<π/4,求(sin2x+2sinx)/(1 - tan2x) -
蔺凭汤13128259807 ______ cos(x+π/4)=cosxcosπ/4-sinxsinπ/4=√2/2*(cosx-sinx)=3/5 cosx-sinx=3√2/5-sin2x=cos(2x+π/2)=2cos²(x+π/4)-1=-7/25 sin2x=7/25 cosx-sinx=3√2/5 sinx=cosx-3√2/5 平方 sin²x=1-cos²x=cos²x-6√2/5*cosx+18/252cos²x-6√2/5*cosx-7/25=0 ...

宓湛庭1765cos 2x/cos[(派/4)+x] -
蔺凭汤13128259807 ______ 方法1 cos 2x/cos[(派/4)+x]=(cos²x-sin²x)/(cosπ/4cosx-sinπ/4sinx)=(cosx+sinx)(cosx-sinx)/[√2/2(cosx-sinx)]=√2(cosx+sinx)=2(√2/2sinx+√2/2cosx)=2sin(x+π/4) 方法2 原式=sin(π/2+2x)/cos(π/4+x) =2sin(π/4+x)cos(π/4+x)/cos(π/4+x) =2sin(π/4+x)

宓湛庭1765已知sin(x - π/4)=1/3,则cos(π/4+x)=? 这一步是怎么得来的cos[π/2 - (π/4 - x)] -
蔺凭汤13128259807 ______ 诱导公式 sin(π/2-a)=cosa 即两个角(π/2-a)+a=π/2 两角互余,则余函数值相等 (x-π/4)+(π/4+x)=π/2 两角互余,所以 sin(π/4-x)=cos[π/2-(π/4-x)]=cos(π/4+x)=-1/3

宓湛庭1765已知sin(π/4 - x)=5/13,x属于(0,π/4),求(cos2x)/cos[(π/4)+x] -
蔺凭汤13128259807 ______ x属于(0,π/4)0所以cos(π/4-x)>0 [sin(π/4-x)]^2+[cos(π/4-x)]^2=1 所以cos(π/4-x)=12/13 sin(π/2-2x)=2sin(π/4-x)cos(π/4-x)=120/169 所以cos2x=sin(π/2-2x)=120/169 cos(π/4+x)=sin[π/2-(π/4+x)]=sin(π/4-x)=5/13 所以(cos2x)/cos(π/4+x)=(120/169)/(5/13)=24/13

宓湛庭1765cos(x+π)等于多少 -
蔺凭汤13128259807 ______ cos(x-π/2)等于sinx. 解答过程如下: cos(x-π/2) =cos(-(π/2-x))(这里是把x-π/2化成-(π/2-x)) =cos(π/2-x)(这里是因为cos-x=cosx,cosx是一个偶函数) =sinx 扩展资料: 设α为任意角,弧度制下的角的表示: (1)sin(π+α)=-sinα. (2)cos(π+α...