让ABC ABC分别是的角度A BC三角形两侧M =(COSC / 2,正弦/ 2),N =(COSC / 2,正弦/ 2),1角C 2已知C = 7/2倍的根三角形= 3/2 A + B的价值

问题描述:

让ABC ABC分别是的角度A BC三角形两侧M =(COSC / 2,正弦/ 2),N =(COSC / 2,正弦/ 2),1角C 2已知C = 7/2倍的根三角形= 3/2 A + B的价值

让载体OM,对模具|
OM |,| | COS∠MON = COS?= 1/2 =(OM *)/(| OM | * | |)OM * = COSC / 2 *
cosC/2-sinC/2 *正弦/ 2 = COSC | OM | = 1,| | = 1 1/2 = COSC,C SINC =√3/2S = 3
*√3/2 =,AB 1/2absinC = 6