Question

数学题2道【初三】只要求大致过程.

Answer 1

1、∵ABDE四点共圆

∴∠BAC+∠BDE=180

∵∠BDE+∠CDE=180

∴∠BAC=∠CDE

∴△CDE≈△CAB

CA/CD=√(S△ABC/S△DBC)=3

AD/AC=√(AC^2-CD^2)/AC=2√2/3

2、S△AOB/S△AOD=3,即

BO/OD=√3

△AOD≈△COB

S△AOD/S△COB=(OD/OB)^2=1/3