The voltage across a 50uF capacitor is described by the equation vC=(18V)cos(200t), where t is in seconds.
The first part asked for voltage across the capacitor at t=0.011s which is -11V.
What is the capacitive reactance? Xc=1/(2pi*f*c) but what is f? Is this the right approach?
What is the peak current? Ic=Vc/Xc, is Vc (18V)cos(200*.011s)?