CHO A= ( –2; –1) ; B= ( 4; –3 ). COS(A; B) =
Câu 28: Cho
a
= ( –2; –1) ;b
= ( 4; –3 ). cos(a
;b
) = ? A. –5
5
C.3
2
D.1
2
5
B. 25
a
= ( –2; –1) ;b
= ( 4; –3 ). cos(a
;b
) = ? A. –5
5
C.3
2
D.1
2
5
B. 25