向量u=向量a+t向量b=（cos23°+tcos68°,cos67°+tcos22°）(t属于R),∴u^=(cos23°+tcos68°)^+(cos67°+tcos22°）^=(cos23°+tsin22°）^+(sin23°+tcos22°)^=1+t^+2t(sin22°cos23°+cos22°sin23°）=1+t^+2ts...