Net torque on triangular loop of wire

The problem is attached. I'm trying to do 2.a), which asks for the net torque on the loop. I've obtained the following values of forces: [itex]F_{PQ}=0N, F_{PR}=12N[/itex] in to the plane, [itex]F_{QR}=12N[/itex] out of plane. But I don't know how to calculate the net torque if the loop is pivoted about an axis that lies along side PR. I know the torque is Frsinθ, but what are r and θ in this case?

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