Question

九年级下册数学第131页第二题怎么做?很急!急用!

Answer 1

∵∠A=68°

∴∠ABC+∠ACB=180°-68°=112°

∵点I为△ABC的内心

∴BI平分∠ABC,CI平分∠ACB

∴∠IBC+∠ICB=1/2(∠ABC+∠ACB)=56°

∵∠BIC+∠IBC+∠ICB=180°

∴∠BIC=180°-56°=124°