Question

what kind of error may happen when you are measuring the height of nperson taller than you?why should we do to avoid the error

Answer 1

If you are measuring the height of a person taller than you then the error will happen will that you can tell him wrong measuring because your eyes will be at lower level than his head(parallax error). by this you'll measure wrong and you'll tell the person increased height than original.
to avoid this you should get something to stand on so that you can see the person head perpendicularly and tell him the correct height.