Question

Two forces P and Q are in ratio P:Q=1: 2.IF
magnitude of their resultant is √8P and angle
between P and Q is X then value of cos (X) is.​

Answer 1

Answer:

Step-by-step explanation:

Answer Text

tan−1(12)

45∘

30∘

60∘

Answer :

A

Solution :

tanα=QsinθP+Qcosθ

3–√2=sinθPQ+cosθ⇒3–√2=sinθ(1/2)+cosθ⇒34=(2sinθ1+2cosθ)2

⇒3(1+2cosθ)2=16sin2θ

⇒3(1+4cos2θ+4cosθ)=16(1−cos2θ)

⇒3+12cos2θ+12cosθ=16−16cos2θ

⇒28cos2θ+12cosθ−13=0⇒ cosθ=(1)/(2),−0.92