mc~~~~~~~~2

1.B
2.A
3.D
4.B

2007-07-25 10:56:52 補充：
1. x=p(corr. angles, AB//CD)r=p(vert. opp. angles) =xSo, I and III are correct.i.e. Answer:B

2007-07-25 10:57:13 補充：
2.Because sum of interior angles of n-sided polygon = 180(n-2)and n must be an integer (since number of sides must be an integer)So, Sum of interior angles of n-sided polygon must be a multiple of 180.but 90 is not a multiple of 180i.e. Answer: A

2007-07-25 10:57:22 補充：
3.Exterior angles of a convex polygon must be smaller than 180and a regular polygon must be a convex polygon.So, 360 is impossible to be the size of a regular polygon.i.e. Answer:D

2007-07-25 10:57:31 補充：
4.Angle AOD=180(adj. angles on st. line)i.e. Angle AOB Angle BOC Angle COD=180Angle AOB Angle BOC=125Angle BOC Angle COD=80(Angle AOB Angle BOC) (Angle BOC Angle COD)=125 80(Angle AOB Angle BOC Angle COD) Angle BOC=205180 Angle BOC=205Angle BOC=25i.e. Answer:B

18.B
19.A
20.D
21.B

18) B
x will never = q unless x=90

19) A

For a triangle, the min. sum =180

20) D

360 = WHOLE ANGLE

21) B

AOC=(180 - 80) =100
BOC=125-100=25