Grade 12 physics

You are standing 2.7m from the centre of a spinning merry-go-round holding one end of a string tied to a 120g mass. The merry go round has a period of 3.9s. The question then asks for the angle the string makes with the vertical and the magnitude of ft.

I solved for the angle by setting ft=mg/cos and ftx=fc. The angle was 36, which is correct. Now im trying to solve for ft, which should be mg/cos but for some reason i keep getting the wrong answer. Any suggestions?