400cos45 ->400/√2 -> =200√2 I undon't derstand where 200√2 come from.

Answer 1

(400 / √2) (√2 / √2) = (400 * √2) /( √2 * √2) = 400 √2 / 2 = 200 √2
the idea was to get the √2 out of the denominator