Please bantuin.. No 9 sampai 11 beserta caranya

11. dik. |a| = 4
|b| = 10
sudut = 60°
dit. a.(b + a)
penyelesaian
a.(b+a)
|a|.|b|. cos alfa + |a|.|a|. cos alfa
4.10.cos 60° + 4.4.cos 0°
4.10.(1/2) + 4.4.1
4.5 + 16
36

13. dik. u = 2i-3j+k
dit. |u| ?
penyelesaian
|u| = akar 2^ + (-3)^ + 1^
= akar 4 + 9 + 1
= akar 14

14. BA = 2-(-1)
-1-1
1-1
= 3
-2
0
|BA| = akar 3^ + (-2)^ + 0^
= akar 9 + 4
= akar 13