Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

In the pyramid of base ABC and the apex S the heights AA', BB', CC', SS' cross in one point lying within the pyramid. Point O is the center of the sphere circumscribed on this pyramid. Prove that if SO is perpendicular to the plane A'B'C', then the pyramid ABCS is regular.

share|cite|improve this question

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.