What must be the minimum height of a plane mirror so that a boy of height 162 cm can view himself from head to toe?
A. 40.5 cm
B. 81 cm
C. 162 cm
D. 324 cm
It would be B. 81 cm?
Half his height, sketch it.
To determine the minimum height of a plane mirror required for a boy of height 162 cm to view himself from head to toe, we need to consider the principle of reflection.
When a person stands in front of a plane mirror, the height of the mirror should be half of the person's height for them to see their entire body. This is because the mirror reflects light in such a way that the distance from the person's head to the mirror is the same as the distance from the mirror to their feet.
So, to calculate the minimum height of the mirror, we divide the boy's height by 2:
162 cm / 2 = 81 cm
Therefore, the correct answer is B. 81 cm.