已知x+y+z=π,证明sin(x+y)+sin(y+z)+sin(z+x)≥sin2x+sin2y+sin2z

已知x+y+z=π,证明sin(x+y)+sin(y+z)+sin(z+x)≥sin2x+sin2y+sin2z 三角不等式证明证明sin(x+y)+sin(y+z)+sin(z+x)>sinx+siny+sinz+sin(x+y+z) 已知(x+y+z)^2=x^2+y^2+z^2,证明x(y+z)+y(z+x)+z(x+y)=0 已知整数x,y,z满足(x-y)(y-z)(z-x)=x+y+z,证明:x+y+z是27的倍数 证明sinx+siny+sinz-sin(x+y+z)=4sin((x+y)/2)sin((x+y)/2)sin((x+y)/2) 帮忙解道题 ,已知x+1/y=y+1/z=z+1/x ,证明x+y+z=1 证明x-(y-z)=x-y+z 证明sin(x+y)sin(x-y)=sinx-siny 已知 x/(y+z)+y/(z+x)+z/(x+y)=1求 (x*x)/(y+z)+(y*y)/(x+z)+(z*z)/(x+y)=? 若z=x+iy,试证明|sin²z|=sin²x+sh²y 2sin(2+2y-3z)=x+2y-3z,证明δz/δx+δz/δy=1 已知三个正实数x y z,且x+y+z=1,证明(x^2+y^2+z^2)(z/(x+y)+x/(y+z)+y/(z+x))>=1/2 已知 x,y,z都是正实数,且 x+y+z=xyz 证明 (y+x)/z+(y+z)/x+(z+x)/y≥2(1/x+1/y+1/z)^2 试证明(x+y-2z)+(y+z-2x)+(z+x-2y)=3(x+y-2z)(y+z-2x)(z+x-2y) 用行列式的性质证明：y+z z+x x+y x y z x+y y+z z+x =2 z x y z+x x+y y+z y z x 这个怎么证? 求全微分z=e^[sin(x+y)]*y^x 证明x*x*x+y*y*y=z*z*z(x.y.z为正整数)不成立. 证明 ：x/(y+z)+y/(z+x)+z/(x+y)>=3/2其中 x,y,z>0