对于角的平分线,要掌握以下几点:一是角的平分线是一条射线,而三角形的角平分线是一条线段;二是角的平分线的性质及判定;三是利用角平分线翻折构造全等三角形.例1(1)如图1,△ABC中,若P点是∠ABC和∠ACB的平分线的交点,求证:∠BPC=90°+1/2∠A.(2)如图2,△ABC中,若P点是∠ABC和外角∠ACE的平分线的交点,求证:∠P=1/2∠A. For the bisector of the angle, to grasp the following points: First, the bisector of the angle is a ray, and the angle bisector of the triangle is a line segment; the second is the nature of the bisector of the angle and determine; the third is the use of angle bisector (1) In Figure 1, △ ABC, if P is the intersection of 平ABC and 平ACB bisector, verify: ∠BPC = 90 ° + 1 / 2∠A. (2 ) As shown in Figure 2, △ ABC, if P is the intersection of 平ABC and the outer corner ∠ACE bisector, verify: ∠P = 1 / 2∠A.