题目如图1,PA、PB、PC是⊙O的三条弦,PA=a,PB=b,∠APC=30°,∠BPC=60°,求弦PC的长.下面我们以此题为例来分析关于计算弦长的几种方法.解法一:灵活作垂线如图2,连结AB、AC,过点A作AE⊥PC于点E.在Rt△APE中,因为∠APC=30°,PA=a,所以AE=a2,PE=3姨a2.又因为∠ACP=∠PBA,∠AEC=90 The problem is shown in Figure 1. PA, PB, and PC are the three chords of ⊙O, PA=a, PB=b, ∠APC=30°, ∠BPC=60°, and the length of the string PC. Here we take this example as an example. To analyze several methods for calculating chord length. Solution one: Flexibly make a vertical line as shown in Figure 2, link AB, AC, point A as AE⊥PC at point E. In Rt A APE, because ∠APC=30° , PA = a, so AE = a2, PE = 3 姨 a2. Also because ∠ ACP = ∠ PBA, ∠ AEC = 90