$\text{ Let }f(x+y)=f\left(x\right)f\left(y\right)\text{ for all }\mathrm{x}\text{ and }\mathrm{y}\text{ and }\mathrm{f}\left(1\right)=2\text{ . If in a triangle }\mathrm{ABC},\mathrm{a}=\mathrm{f}\left(3\right)\text{ , b = f(1) + f(3), c = f(2) + f(3) then 2A is equal to }$