If two forces and act on such an angle that their resultant force is equal to force , then if is doubled then the angle between the new resultant force and will be
Step 1: Given data
Resultant force of and is and it is equal to .
Step 2: Formulas used
From the law of cosines,
where , , and are the three sides of a triangle and is the angle opposite to side
Step 3: Solution
Let the angle between the forces and is .
From the law of cosines an triangle law of vector addition, we have
When the is doubled, let the new resultant make an angle with .
It can be written as,
Thus, the new resultant is at to .
Hence, option D is correct.