V1V2=S1S2V_{1} V_{2}=S_{1} S_{2}V1V2=S1S2
S1 V1=S2 V2\mathrm{S}_{1} \mathrm{~V}_{1}=\mathrm{S}_{2} \mathrm{~V}_{2}S1 V1=S2 V2
V1S2=V2S1V_{1} S_{2}=V_{2} S_{1}V1S2=V2S1
V1 S1=V2 S2\frac{\mathrm{V}_{1}}{\mathrm{~S}_{1}}=\frac{\mathrm{V}_{2}}{\mathrm{~S}_{2}} S1V1= S2V2