use the quadratic formula ...
A mass m = 8.5 kg is suspended from a string of length L = 1.37 m. It revolves in a horizontal circle. The tangential speed of the mass is 2.75 m/s. What is the angle q between the string and the vertical (in degrees)?
i know F= m v^2 /R...
Tsinx = m v^2/Lsinx
Tcosx - mg = 0
i'm having trouble solving for x though...