分析，我給妳提供壹個方法，設OC=xOA+yOB，(x，y為常數)OA * OB = | OA | | OB | * COS 75 = (√ 6-√ 2)/4，| OC | = | XOA+YOB | = √ (x？OA？+y？OB？+2xyOA*OB)=5，那麽，x？+y？+(√6-√2)* xy/2 = 25.1OA * OC+OB * OC = | OA | * | OC | * cos 30+| OB | * | OC | * cos 45 = 5(√3+√2)/2，OA * OC+OB * OC =(OA+OB)* OC =(OA+OB)(xoa+yob)= x+y+(x+y)* OA * OB =(x+y){ 1+(.
解決這個問題的過程太麻煩了。我已經給妳提供了想法。
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