如图,AB.CD.EF相交于O点,EF⊥AB,OG为∠COF的平分线,OH为∠DOG的平分线.若∠AOC:∠COG=4:7,求∠DOF.∠DOH的大小.
问题描述:
如图,AB.CD.EF相交于O点,EF⊥AB,OG为∠COF的平分线,OH为∠DOG的平分线.若∠AOC:∠COG=4:7,求∠DOF.∠DOH的大小.
答
1、∵EF⊥AB∴∠AOF=90∵OG平分∠COF∴∠COG=1/2∠COF∵∠AOC:∠COG=4:7∴∠COG=7/4∠AOC∴1/2∠COF=7/4∠AOC∴∠COF=7/2∠AOC∵∠AOC+∠COF=∠AOF=90∴∠AOC+7/2∠AOC=90∴∠AOC=20∴∠COF=7/2∠AOC=...