The formula for calculating the height of a friend's image from 4.2m away is: height = (actual height of friend x distance to friend's image) / distance to friend.
The height and distance measurements should be in the same units, such as meters or feet.
The distance to the friend's image is important because it is used to determine the angle at which the friend's image is being viewed. This angle is crucial in accurately calculating the height of the friend's image.
Yes, this formula can be used for any distance to the friend's image as long as the actual height of the friend and the distance to the friend are known.
No, this calculation is not affected by the height of the observer. The formula only takes into account the actual height of the friend and the distance to the friend's image.