If the architectural plans show the rough opening of a window to be 3'-3" x 4'-9" , the height of the opening should actually measure

height of the opening actually measure is 4'-9"

Explanation:

given data

window size = 3'-3" x 4'-9"

solution

height of the opening should actually measure will be 4'-9" in 3'-3" x 4'-9"

because according to architectural plan height can not be more than the opening size of window

and we can't take smaller height also

so fit in opening window we should take same height of  height of opening window and that is here 4'-9"

so here height of the opening actually measure is 4'-9"