向量m.向量n=2√2cosa+cosasina+2√2sina-sinacosa.=2√2(sina+cosa)=1.=2√2*√2sin(a+π/4)=1.∴sin(a+π/4)=1/4.cos(a+7π/12)=cos(a+π/4+π/3).=cos(a+π/4)cosπ/3-sin(a+π/4)sinπ/3.=(√15/4)*(1/2)-(1/4)*...