Consider the annular triangular fin fabricated from an alloyed aluminum(k=180 W/m*K) of lenght L=10mm, tickness t=1mm. The base temperature of the fin is Tb=250 Celcius degrees , and the fin is exposed to a fluid of temperature Too =25 Celcius degrees. Assuming a uniform convection coefficient of h=100 W/m^2*K over the entire fin surface, determine the fin heat tranfer rate; efficiency Nf and the effectiveness Ef.