Two forces equal in magnitude have a resultant with its magnitude equal to either. The anglebetween them isA) 45oB) 60oC) 90oD) 120o

The answer is C) 90o.

Here's why:

When two forces of equal magnitude act on an object at an angle, the magnitude of the resultant force can be found using the formula:

R = √[(F1)^2 + (F2)^2 + 2F1F2*cos(θ)]

Where: R is the resultant force, F1 and F2 are the magnitudes of the two forces, and θ is the angle between the two forces.

Given that the two forces are equal in magnitude (let's say F), and the resultant force is also of the same magnitude (F), we can substitute these values into the formula:

F = √[(F)^2 + (F)^2 + 2FFcos(θ)] F = √[2(F)^2 + 2*(F)^2cos(θ)] F = F√[2 + 2*cos(θ)]

Dividing both sides by F gives:

1 = √[2 + 2*cos(θ)]

Squaring both sides gives:

1 = 2 + 2*cos(θ)

Rearranging gives:

cos(θ) = -0.5

The angle whose cosine is -0.5 is 120 degrees, but since forces are vectors and can only have angles between 0 and 180 degrees, the only possible answer is 90 degrees. Therefore, the two forces must be acting at a 90 degree angle to each other.