Two forces of magnitudes 8N and 15N act at a point, if the resultant force is 17N, the angle between forces is equal to:

The resultant of two vectors:

P

  and    

Q

 is given by  

R=  

P  

2

+Q  

2

+2PQcosθ

where, P and Q are magnitudes of two vectors and θ is the angle between two vectors.

Here θ=?  P=8N  Q=15N  R=17N

Therefore,

17=  

8  

2

+15  

2

+2×8×15cosθ

289=64+225+240cosθ

289=289+240cosθ

289−289=240cosθ

cosθ=0

cosθ=cos90

θ=90  

0

Explanation: