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## Homework Statement

The voltage across and current through a device are given by:

v(t)= 5cos(4∏t)V

i(t) = 0.1cos(4∏t)A

determine the instantaneous power p(t) at t=0 and t = 0.25s

## Homework Equations

p=vi

## The Attempt at a Solution

for t=0 I got p=0.5W

for t=0.25 I got p = 0.5W

the textbook says at t=0 it should be 0. Does power always equal 0 at t=0 or did i mess up on my calculation?