Question

Sa se determine produsul scalar al vectorilor:
a) a=i+j, b=2i-j
b) a(5, -1) b=3i+14j
c) a(3, -2) b(2,3)

Answer 1

Salut,

a•b = XaXb+YaYb.

a)
a = i+j
b = 2i-j
a•b = 1•2-1•1 = 2-1 = 1.

b)
a(5;-1) → a = 5i-j.
b = 3i+14j
a•b = 5•3-1•14 = 15-14 = 1.

c)
a(3;-2) → a = 3i-2j
b(2;3) → b = 2i+3j
a•b = 3•2-2•3 = 6-6 = 0.

Succes!

Answer 2

1*2+1*(-1)=2-1=1


5*3 +14*(-1)=15-14=1



3*2-2*3=6-6=0 (produs scalar este 0, vectorii sunt perpendiculari)