r2=cos2a 怎么画
来源:学生作业帮助网 编辑:作业帮 时间:2024/08/04 02:23:16
![r2=cos2a 怎么画](/uploads/image/f/769590-54-0.jpg?t=r2%3Dcos2a+%E6%80%8E%E4%B9%88%E7%94%BB)
cos2a=cos²a-sin²a.二倍角公式=cos²a-(1-cos²a).用公式sin²a+cos²a=1=2cos²a-1
证明:串联U1:U2=R1:R2因为I1=I2=II=U1/R1(1)I=U2/R2(2)联立(1)(2)两式相除得U1:U2=R1:R2证明:并联I1:I2=R2:R1因为U1=U2=UU1=I1R
sinA=2/3,cos2A=1-2sin²A=1-2*(2/3)²=1-8/9=1/9
cos2a=1-2(sina)^2=1-2/9=7/9
原式=-(cos2a-sin2a)/[cos2a(sina+cosa)]=-cos2a/[cos2a(sina+cosa)]=-1/(sina+cosa)
左边平方差=(sin²a+cos²a)(sin²a-cos²a)因为sin²a+cos²a=1所以左边=sin²a-cos&sup
sinA=1/3则cos2A=1-2sin²A=1-2*(1/3)²=1-2/9=7/9
cos(A+B)的平方-sin(A-B)的平方=[cos(A+B)-sin(A-B)][cos(A+B)+sin(A-B)]=[cosAcosB-sinAsinB-sinAcosB+cosAsinB]
你的电路如图所示: 1、电路的电流 :I1=I2+I3 ,I3=I1-I2 . 2、电路R2与R3并联:两个支路的电流与电阻成反比. &nb
cos2a=cosa^2-sina^2=1-2sina^2=2cosa^2-1
cos²a=cos²a/(sin²a+cos²a)=1/(sin²a/cos²a+cos²a/cos²a)=1/(1+t
这个等式是不成立的.假设a=30,那么sin4a-cos4a=sin120-cos120=sin60+cos60=/2sin2a-cos2a=sin60-cos60=/2
sin2a+sina/cos2a+cosa+1=(2sinacosa+sina)/(2cos²a+cosa)=sina(2cosa+1)/[cosa(2cosa+1)]=sina/cosa=
证明:1-cos(2A)=2*[(sinA)^2]1+cos(2A)=2*[(cosA)^2]sin(2A)=2sinA*cosA==>(1+sin2A-cos2A)/(1+sin2A+cos2A)=
证:∵(sin2a-cos2a)^2=sin²2a+cos²2a-2sin2acos2a而sin²2a+cos²2a=1,2sin2acos2a=sin4a,∴
分子=sin²a+cos²a+2siacosa-(cos²a-sin²a)=(sina+cosa)²-(cosa+sina)(cosa-sina)=(
sin2a=cos2a*2=2cos2acos2a=-sin2a*2=-22sin2a
(sin2a-cos2a)^2=sin2a^2+cos2a^2-2*sin2a*cos2a=1-2*sin2a*cos2a=1-sin4a因为sin2a^2+cos2a^2=12*sin2a*cos2
sin2a=2sina*cosacos2a=cos²a-sin²a=2cos²a-1=1-2sin²a所以(1+cos2a)/sin2a-sin2a/(1-co
1/(1/R1+1/R2)=1/(R2/R1R2+R1/R1R2)=1/[(R1+R2)/R1R2]=R1*R2/(R1+R2)希望可以帮助你,满意请采纳,