conical pendulum,, could somebody help please,,

calculate the tension and angular speed in a 2m string attached to a 2kg bob that is moving in horizontal circles of 0.5m radius.

i have traweld the net and the same formula keeps poping up Tcos(angle)=mg.

after doing a sketch of the problem the first thing i did was to find the upper angle,

i used SOH(OPP/HYP) 0.5M/2M=0.25 tan-1 0.25= 14 degrees.so far so good.its now i get confused, i understand that the T refers to tension, cos is cosine and mg is mass x gravity.

the book says T=mg/cos(angle),,,,,T=2x9.8/0.25= 78.4N where does the 0.25 come from i thought a cosine needed adj/hyp. the above 0.25 i got was from the SOH value, sorry if this is a bit long winded for you people but this is the problem with home study i just need it simplifying and explaining thanks,