如图,已知∠α的一边在x轴上,另一边经过点A(2,4),顶点为(﹣1,0),则sinα的值是( )
A:25
B:55
C:35
D:45
The little boy caught some ____ (butterfly) and put them into a big bottle.
若方程组x+2y=1k-1x+k+1y=2的解x与y相等,则k的值为( )
1ab + 1(a+1)(b+1) + 1(a+2)(b+2) +…+ 1(a+2007)(b+2007) .