S89=sin
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sin(-x)=sin(x),cos(-x)=-cosx对吗?不对,反了应sin(-x)=-sin(x),cos(-x)=cosx
是tan=sin/cos
cos(π/6)=1-2[sin(π/12)]^2所以sin(π/12)=√[(1-cos(π/6)/2]=√[(3-√3)/6]
sin(x+y)sin(x-y)=-1/2(cos(x+y+x-y)—cos(x+y-x+y))=-1/2(cos2x—cos2y)=-1/2(1-2(sinx)^2-1+2(siny)^2)=(si
sinα+sinβ=2sin[(α+β)/2]cos[(α-β)/2]
左边=(sinacosb+cosasinb)(sinacosb-cosasinb)=sin²acos²b-cos²asin²b=sin²a(1-sin
sin2+cos2=1是成立的,这是个公式.sin+cos=1是不对的,这只有当角度为90或0的时候才成立同理,根号下sin+cos=1也只有在角度为90或0的时候才成立
这个方程无解取区间[-π,π]-1
dy/dx相当于对x进行求导:dy/dx=y'=2x*cos[sin(x^2)]*cos(x^2)由于:sinx=cosx,sin(x^2)=2x*cos(x^2)
sin(arcsinx)=xcos(arccosx)=xcos(2arcsinx)=1-2[sin(arcsinx)]^2=1-2x^2
(sinx)^4+(cosx)^4=1即(sinx)^4+(cosx)^4+2(sinx)^2(cosx)^2-2(sinx)^2(cosx)^2=1即[(sinx)^2+(cosx)^2]^2-2(
求导原计算是y'=dy/dx那么sin'wt=dsinwt/dt=(dsinwt/dwt)*(dwt/dt)(分子分母同时乘以dwt,再分开写成两个式子)=(wt)'*coswt你题目中的结果不正确.
sina+sinb=sin[(a+b)/2+(a-b)/2]+sin[(a+b)/2-(a-b)/2]=sin(a+b)/2cos(a-b)/2+cos(a+b)/2sin(a-b)/2+sin(a+
sin^2/(sin-cos)-(sin+cos)/(tan^2-1)=sin^2/(sin-cos)-(sin+cos)/[(sin^2/cos^2)-1]=sin^2/(sin-cos)-(sin
sin(45°)=COS(315°)=45°=315°
Sin[a+b]Sin[a-b]积化和差公式得=1/2(-Cos[2a]+Cos[2b])余弦二倍角公式得=Sin[a]^2-Sin[b]^2Sin[80°]Sin[40°]=Sin[60°+20°]
应该是sinA+sinB=2sin[(A+B)/2]cos[(A-B)/2]A=(A+B)/2+(A-B)/2.B=(A+B)/2-(A-B)/2所以sin(A+B)/2cos(A-B)/2+cos(
答:sin^2a+sin^2(a+60)+sin^2(a+120)=3/2.证明:左边=sin^2a+sin^2(a+60)+sin^2(a+120)=sin^2a+(sinacos60+cosasi
sin平方30度=(sin30)平方=(1/2)^2=1/4sin平方60度=(sin60)平方=(√3/2)^2=3/4