4. A semiinnite heat-conducting plate of width o. is extended along the positive .rattis with one corner at {till} and the other at {IL o}. The side of width EL is held at temperature T\". and the two long sides are held insulated such that array = ['1 along these sides. The temperature obeys the heat diffusion equation: Find the temperature of the plate once in equilibrium {when the time derivative is U}