from v) , when T=0. V^2 = 3gl
then take iii) V^2 = v^2 + 2gl(1-cos@) and equate the V^2
so 3gl = v^2 + 2gl(1 - cos@)
since you found @.. cos@ = -1/3 , it should end up as v^2 = gl(3 - 2 -2/3)
i don't think you get a mark for that, so dont worry about it.