The voltage across a 60μF capacitor is described by the equation vC =(18 V) cos(200t), where t is in seconds.
What is the voltage across the capacitor at t =0.010 s?
2. Relevant equations
3. The attempt at a solution
When you use degrees the answer is 18V and when you use radians its -7.5 V (the correct answer). Can someone explain why you must use radians here? It’s been a while since using these in math class so the simpler explanation the better if you wouldn’t mind 🙂 (maybe I am missing something obvious).