Question

Two vectors have magnitude 3 and 4 units respectively.What should be the angle between them if the magnitude of the resultant is 1 unit

Answer 1

Howdy!!

your answer is ----

LET,vector A = 3 unit and vector B = 4unit

Given, their resultant is 1 unit .

alos, let angle between them is ∅

so √A^2+B^2+2ABcos∅ = 1

=> A^2+B^2+2ABcos∅ = 1

=> 3^2 + 4^2 + 2×3×4cos∅ = 1

=> 9+16+24cos∅ = 1

=> 25+24cos∅ = 1

=> cos∅ = -24/24

=> cos∅ = -1

=> cos∅ = cos180°. [ cos180° = -1 ]

=> ∅ = 180°


hence, angle between two vectors is 180°

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hope it help you

Answer 2

here a=3,b=4. a^2+b^2+2abcosx=R^2. 9+16+24cosx=1.
24cosx=-24
cosx=-1
x=180°