# two vectors of equal magnitude have a resultant equal to either of them, then the angle between them will be equal to...?

Hello!

The resultant (R) of two forces (A and B) is mathematically represented as

R2 = A2 + B2 + 2ABCosθ

where θ is the angle between forces A and B. Now, as all three forces are equal, so

let R = A = B = x

So,

x2 = x2 + x2 + 2x.xCosθ

or  x2 = 2x2 (1 + Cosθ)

1/2 = 1 +  Cosθ

thus ,  Cosθ =  -1/2

or θ = 120o

The answer was calculated correctly by @prakharmilitary.

Hello @prakharmilitary ! good job, keep it going!

• 55

Basically such a situation is not possible, but if we consider the motion in only a particular axis like X or Y. then the angle must be 90 degrees. then the component in the direction of anyone of them is equal to them.

• -1

But in book D.C.PANDEY Mechanics..  it is given that this condition is possible...

• -4

A^2=2A^2+2*A*A*cos x

A^2-2A^2=2A^2*cosx

-A^2/2A^2= cos x

-1/2=cos x

then find cos x

• 2

and then cos equals 120 degree

• 2
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