The sum of two forces P→  and Q→  is  R→ such that R→=P→ . The angle θ (in degrees) that the resultants of 2P→  and Q→  will make with  Q→ is ____

From triangle law of vector addition , we can say that angle between  2P→+Q→ and Q→  is 90º  Alternate solution  P→+Q→=P→               P2+Q2+2PQcosθ=P2       ⇒Q+2Pcosθ=0           ⇒cosθ=-Q2P tanα=2Psinθ2Pcosθ+Q=∞∵2Pcosθ+Q=0α=90ºSo angle between  2P¯+Q¯ and  Q¯ is 90º