How do I prove that if -LSB- math -RSB- \ frac -LCB- b -RCB- -LCB- a -RCB- = \ frac -LCB- d -RCB- -LCB- a -RCB- -LSB- / math -RSB- , then -LSB- math -RSB- b = d -LSB- / math -RSB- ?
What is the craziest math or physics theorem you know ?