Verified answer

R=po*L/S   S=π*d²/4    R=4*po*L/(π*d²)

d1/d2=√3    R1=R2/3

d1/d2=1/2    R1=4*R2

d1/d2=1/√10   R1=10*R2

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R=Ro*(1+α*ΔT)    R=Ro+ΔR

α=ΔR/(Ro*ΔT)=500/(100*100)=0.05

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