以圆为背景的平面向量问题,是一类较为新颖的问题,常出现在模拟题和高考题中,本文对这类问题进行探究,希望对大家的学习有所帮助.1.求值问题例1(2005年全国卷)△ABC的外接圆的圆心为O,两条边上的高的交点为H,→OH=m(→OA+→OB+→OC),则实数m=.解法特殊化:设为直角三角形,则 The plane vector problem with the circle as the background is a relatively new type of problem, which often appears in the simulation question and the college entrance examination question. This article explores such questions and hopes to be helpful to everyone’s learning. 1 (2005 national volume) △ ABC circumcircle of the center of O, the intersection of the two sides of the high H,  → OH = m ( → OA +  → OB +  → OC), the real number m =. Solution specialization: set to a right triangle, then