My question is about the LED connection through a resistor ?

Hi as I am a New bee here , I have an doubt on using a right specs of electronic components. My scenario is I'm using a TRICOLOR LED w.hich is 2v and 50mA in spec and I'm using a 12v power supply and my concern is about the resistor to be used. Now I use a 200 ohm resistor to rectify the voltage to 2v(as per the theoretical calculation) and LED is working fine. But the problem is with the resistor because after a while the resistor gets too hot and it even melts my insulating rubber. Is it the behavior of the resistor which is common or am I using a wrong spec of resistor for the above scenario. Pls If anyone can help me here can explain about this and give me. Solution...?