A conduction heat wave is caused to pass through a metal bar of average temperature Tmean = 38.0 ¢XC, altering its temperature sinusoidally with an amplitude of Ti = 3.00 ¢XC. The equation which gives the temperature, T(x,t), of the metal bar at any place x (in meters) inside it at any time t (in seconds) is:

Question

A conduction heat wave is caused to pass through a metal bar of average temperature Tmean = 38.0 ¢XC, altering its temperature sinusoidally with an amplitude of Ti = 3.00 ¢XC. The equation which gives the temperature, T(x,t), of the metal bar at any place x (in meters) inside it at any time t (in seconds) is: 
T(x,t) = 38 + 3 sin[2£k(0.0290t ¡V5.00x) + 1.5pie]
What is the value of T(x,t) when t = 220.0 s, and x = 0.25m? 
I first worked out the wavelength = 0.2m and then the period = 34.5 seconds then i rewrote the equation to be T(x,t) = 38+3cos[2n(0.029*220/34.5 - 5*0.25/0.2) + 1.5pie] which gave me 35.5 which is not the correct answer of 35.9.  What have i done wrong?