Question

求垂直于向量a=2j+5j+k和X轴的单位向量

Answer 1

let b=(x,y,z) be the vector垂直于X轴=> x =0 (1)垂直于向量a=2j+5j+ka.b =0(2j+5j+k).(x+y+z) =02x+5y+z=0 5y+z =0 (2)单位向量=> x^2+y^2+z^2 =1 y^2 + z^2 =1y^2+25y^2=1y = √26/26 or -√26/26y = √26/26 ,z=...