Question

Two equal forces have the square of their resultant
equal to three times their product. Find the angle
between them
​

Answer 1

Answer:

The square of the resultant force is f1^2 + f2^2 + 2 f1f2cos(theta) where f1 and f2 are the forces and theta is the angle between them. If f1 and f2 are equal to one unit, the square of the resultant is 2 + 2cos(theta) square units. The square of the resultant is equal to three times the product or three square units. Therefore 2 +2cos(theta) = 3, so cos(theta) = 0.5. Therefore theta = 60 degrees.