Question

3 (59) Consider the two vectors A=3i^ + 4j^, B = -8i^+6j^ What is the dot
product A dot B ?


A. zero
B. 50
C. none of these
D. 48​

Answer 1

Answer:

zero

Explanation:

for product of I*j = 0

I*I =1

and j*j=1

hence

3i*(-8i)+4j*(6j)

-24+24=0

Answer 2

Given :-

A = 3i + 4j

B = -8i + 6j

CosØ = A.B/|A|.|B|

|A| = √(ax)² + (ay)²

|A| = √(3)² + (4²)

|A| = √25

|A| = 5 unit

|B| = √(bx)² + (by)²

|B| = √(-8)² + (6)²

|B| = √100 = 10 unit

Now,

CosØ = (3i+4j).(-8i+6j)/5.10 Ans....