过双曲线x^2/9-y^2/16=1左焦点f1的弦长AB长为3则△abf2(f2)(f2为右焦点)的周长是
问题描述:
过双曲线x^2/9-y^2/16=1左焦点f1的弦长AB长为3则△abf2(f2)(f2为右焦点)的周长是
答
18该怎么写步骤呢?∵AF1-AF2=6BF1-BF2=6∴AF1+BF1-﹙AF2+BF2﹚=12∴AF1+BF1=12+﹙AF2+BF2﹚=12+3=15∴△abf2(f2)(f2为右焦点)的周长是AF1+BF1+AB=15+3=18