向量m=(2cosC/2,-sinC),向量n=(cosC/2,2sinC)且向量m⊥向量n.1求角C的大小.2若a^2=2b^2+c^2,求tanA的值

来源：学生作业帮助网编辑：作业帮时间：2024/11/15 10:58:12

x��R�N�0��\��G��C%��lB�P@L��?��9N� u�b�߻{��t��ofá<�:jܯrѩ��ޟ��nZ��j�|��u��~a0� �e�تKӏԍ�Q|�0K��b�|e�AT�_��D��F�D �gЯ�!c��e:�>3�8IR��h��~zo�0�b�}��5x*7�9Չ�� < ,��a�KD1G��.��]��<��dF�u�`/J�4+�n�� ;`m�IF�[��W"�e~��"�R9��-=[�ѭq��4��f��mt�S=�*��]JP

向量m=(2cosC/2,-sinC),向量n=(cosC/2,2sinC)且向量m⊥向量n.1求角C的大小.2若a^2=2b^2+c^2,求tanA的值
向量m=(2cosC/2,-sinC),向量n=(cosC/2,2sinC)且向量m⊥向量n.1求角C的大小.2若a^2=2b^2+c^2,求tanA的值

向量m=(2cosC/2,-sinC),向量n=(cosC/2,2sinC)且向量m⊥向量n.1求角C的大小.2若a^2=2b^2+c^2,求tanA的值
m⊥n
=>m.n=0
(2cos(C/2),-sinC).(cos(C/2),2sinC)=0
2(cosC/2)^2-2(sinC)^2=0
(2(cosC/2)^2-1)-2(sinC)^2+1=0
cosC-2(sinC)^2+1=0
cosC - (2-2(cosC)^2)+1=0
2(cosC)^2+cosC-1=0
cosC = (-1+3)/4 = -1/2
C=2π/3
sinC = √3/2
a^2 =2b^2+c^2
c^2 = a^2+b^2 - 3b^2
by cosine rule
-3b^2 =-2abcosC
cosC = (3b/(2a)) = -1/2
b= -a/3
a^2 =2b^2+c^2
= b^2 + c^2 +b^2
by cosine -rule
-2bccosA = b^2
cosA = -b/(2c)
= -b/ (2asinC/sinA)
tanA = -2asinC/b
= -2a(√3/2))/( -a/3)
= 3√3

设平面向量m=(cosc+sinb,-sinb),n=(cosc-sinb,sinc),m.n=cos^2a 向量m=(2cosC/2,-sinC),向量n=(cosC/2,2sinC)且向量m⊥向量n.1求角C的大小.2若a^2=2b^2+c^2,求tanA的值在△ABC中,向量m=(cosC/2,sinC/2),向量n=(cosC/2,-sinC/2),且向量m与向量n的夹角为π/3,求∠C,已知c=7/2 向量m=(2cosC/2,-sinC) n=(cosC/2,2sinC) 向量m⊥n 角C=60° 若a²=2b²+c²求tanA的值在三角形ABC中,向量m=(2cosc/2,-sinc),n=(cosc/2,2sinc).且m垂直n.若a^2=2b^2+c^2,求tanA的值 (1-cosC)/sinC=tanC/2 三角形ABC中,设向量m=(cosB,sinC),向量n=(cosC,-sinB),且向量m*向量n=1/2,若a=2*根号3,求ABC最大值在△ABC中,向量m=(cosC/2,sinC/2),向量n=(cosC/2,-sinC/2),且向量m与向量n的夹角为π/3,(1)求C,(2)已知c=7/2 ,S△ABC =3√3/2求a+b的值在三角形abc中M向量=(cosc/2,sinc/2)N向量=(cosc/2,-sinc/2),且m向量与n向量夹角为π/3.(1)求C(2)已知c=7/2,三角形ABC的面积为3根号3/2,求a+b 在△ABC中,向量m=（cosC/2,sinC/2）,向量n=（cosC/2,-sinC/2）,且向量m,向量n的夹角为π/3.求角C的值 .已知c=7/2,△ABC面积S=二分之三倍根号三,求a,b的值高二数学数学请详细解答,谢谢! (17 19:35:18)已知向量a=（cosc+sinc,cosc）,向量b=（m,sinc）,（c∈（Л/2,Л】m∈R（1）求函数f（c）=向量a*向量b的解析式（2）求函数y=f(c )最小值在三角形ABC中,向量m=(cosC/2 ,sinC/2),向量n =(cosC/2 ,sinC/2),且向量m,n的夹角为π/3①求角C②已知C=7/2,三角形的面积S=(3√3)/2,求a+b=? 在△ABC中,已知向量m=(sinB,sinA-2sinC),n=(cosA-2cosC,cosB),且m⊥n 求sinC/sinA的值若C=A+π/3,试判断△ABC的形状已知O是锐角△ABC的外接圆的圆心,且∠A=θ,若cosB/sinC*向量AB+cosC/sinB*向量AC=2m*向量AO,则m= 已知O是锐角△ABC的外接圆的圆心,且∠A=60°,若(cosB/sinC)*向量AB+(cosC/sinB)*向量AC=2m*向量AO,则m的值为已知O为锐角三角形ABC的外心,角B=30°,若(向量)BA*cosA/sinC+(向量)BC*cosC/sinA=2m(向量)OB,则实数m的值为? 已知三角形ABC的内角A.B.C 向量m=(cosA-2cosC,cosB),向量n=(2c-a,b),且m平行于n,求sinA/sinC当0 三角形ABC,对边为a,b,c,若向量m=（cosB,sinC),向量n=(cosC,-cosB)且m与n的数量积=1/2求A.