七年级数学复习题
1个回答

3、

CD:AD=3 :(2+4+3)=1 :3

CD=1/3AD

AD=3CD=3CH36=18(cm)

MD=1/2AD=1/2×18=9(cm)

MC=9-6=3(cm)

4、

∠AOC=1/(1+4)∠AOB=1/5∠AOB

∠AOD=1/2∠AOB

∠COD=(1/2-1/5)∠AOB=3/10∠AOB

∠AOB=36÷3/10=120°

5、

(1)∠AON=180°-90°-∠BOM

=90°-1/2∠BOD

=90°-1/2∠AOC

=90°-1/2×50°

=65°

(2)∠DON的余角

=∠DOM

=∠BOM

=1/2∠BOD

=1/2∠AOC

=1/2×50°

=25°

6、

1÷(1/12+1/24)

=1÷3/24

=8(天)