Can anyone help me to convert from degrees to radians because i tried solving: 392*cos60= 230 were 60 is in degrees and 392*cos60= 391.9 were 60 here is in radians and the correct answer is 392*cos60= 196?

Question

phi · Answer

you do not need to convert to radians.  cos(60º)= 1/2

There are certain angles where you should memorize the sin, cos and tangent:
0, 30,  45,   60  and 90º   (or in radians,  0 , pi/6, pi/4, pi/3, pi/2)

phi · Answer

see http://www.analyzemath.com/trigonometry/special_angles.html