Question

plz solve this question..
if two vectors a and b having magnitude 3 and 5 and angle between them is 90° . find their:
a) resultant
b) if angle= 120° then find resultant.
c) find vector a- vector b

Answer 1

a=3

b=5

Resultant when angle 90 = √3^2 + 5^2

= √9 + 25 = √34

b) Resultant = √3^2 +5^2 +2(3)(5) cos120

= √9 +25 +30 cos(180-60)

= √34 - 30×1/2

= √34 -15

= √19

c) a- b

= √a^2 + b^2 - 2ab cos120

= √34 +2(15) 1/2

= √34+15 = √49 = 7