1 true or false

2 D B D C D B

Simple, do not fight.

4 DE =(-2/3)a+( 1/3)b AD =(2/3)(a+b)BC =( 1/3)(a+b)

EF =(- 1/3)(a+b)FA =( 1/3)a-(2/3)b CD =(2/3)b-( 1/3)a

AB=(- 1/3)b+(2/3)a CE=b-a

8 n=2

14θ= arccos(5/8)β= arccos( 19/20)

Group b

1

2 rectangular diagonal

3 diamond diagonal

4 AM=( 1/2)(a+b)

5 external heart

6 MN=2(b-a) AB is the neutral line.

7 (1) 8KM/H is 60 degrees along the current direction.

(2) 4√2KM/H(90+arccos(√6/3)) along the water flow direction.

8 O is BC OA=0.

I haven't studied the required courses. I don't have to do it.

Which one won't? Just ask me.