50

1

2.

six

3.

6 or 10 or 16

4.

5cm

5.

2

6.

50 cm

7.

143

8.

y=- 12/x

9.

1/27

10.

17/32

Two. 1 1- 15

CCBBD

16-20

ADACD

Three. Sketch of 2 1 ( 1)

(2) cm =2BM

Certificate: connection AM,

In △ABC,

∫∠BAC = 120，AB=AC

∴∠B=∠C=30

∫MN vertical division AB

∴BN=AN,BM=AM,∠BNM=∠ANM=90

∵Rt△BNM≌Rt△ANM(HL)

∴∠MAN=∠B=30

∴∠cam=∠cab-∠man= 120-30 = 90

In Rt△AMC, ∠ c = 30.

∴AM= 1/2CM

∴BM=AM= 1/2CM

That is, CM=2BM.

Give me some points! Good luck.