请教2个数学问题

zasdzccUID: 173579

A circular pizza is sliced into 12 equal slices.Doug cuts each slice from the center to the edge in equal parts.If Doug eats 2 slices,what is the sum of the degree measures of the slices he eats?
A) 20
B) 60
C) 120
( N8 s1 G  ?# z' B) pD) 220
+ V  G8 h3 S1 ~9 lE) 240
Answer:B Why?[/SIZE]

; F5 m3 j/ x" q" E9 p; jIf the square root of (36x^2+24xy+4y^2) equal to the square root of (9x^2+54xy+81y^2),then which of the following expressions could be equal to y?
A) y=-2x
; j* X7 k6 g3 h) `B) y=-9x/11
- |' A4 {/ U7 c7 v* w# DC) y=3x/7
# \2 S. {( C) F" E4 o( ^- hD) y=9x/11
E) y=3x
5 m3 u) h# |$ a: x, O8 RAnswer:C Why?[/SIZE]

上杉和也UID: 194375

1）圆周360度
360/12*2=60
! s" Q7 i/ X; l2 q. Q7 m
/ J# Y' v0 g# W' o3 N3 ~3 \2 c1 ?( ^2）36x^2+24xy+4y^2=9x^2+54xy+81y^2
27x^2-30xy-77y^2=0
- h8 o  p" |+ r) T6 E: @5 _1 p(3x-7y)(9x+11y)=0
' p$ ?1 u5 }0 ^, j2 z! N* Iy=3x/7 or y=-9x/11

zasdzccUID: 173579

多谢

cameoUID: 2160222

y=3x/7 or y=-9x/11 [/quote]
为何不选B?

princessWXUID: 2209296

Is there any can tell why?!

4 A* j6 B/ R; J, B, RThis question belong to which year??