Question

If your 6'-6"- (198-centimeter-) tall client had a limited amount of space, what is the smallest size mirror you could have installed that would reflect his full-height image?

Answer

Your image in the mirror is at exactly half scale, so your client would need a mirror that was 3'-3" (99 centimeters) tall and half his width. If you had the top of the mirror set at about 6'-4" (193 centimeters) — the middle height between your client's eyes and the top of his head — your client should be able to see his full reflection.

Test this yourself by holding a tape measure alongside your own image in the mirror. By the way, it does not matter how far away you are from the mirror — your image will still be half-scale.