Question

如图所示,在RT△ABC中,∠C=90°,圆O为三角形ABC的内切圆

Answer 1

∵7／25＝sin∠A＝0.28,故∠A＝16º16′；∠B ＝73º44′ ；

AF＝r·ctg(½∠A) {切线定理；三角函数｝＝1.2×6.997＝8.3964.

同理 BD＝r·ctg（½∠B）＝1.2×0.8030＝0.9636 .

∴AB＝AE＋BE＝AF＋BD＝9.3600；AC＝AF＋CF＝AF＋r＝9.5964；BC＝BD＋r＝2.1636 .