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

What's the easiest way to show x=35 in this diagram?

enter image description here

I eventually figured it out by drawing in two lines and chasing angles:

enter image description here

However, this is a 10th grade question, so I'm sure there's an easier answer.

I sense that I've effectively re-proven some basic theorem about secants/chords.

share|cite|improve this question
up vote 2 down vote accepted

This is the inscribed angle theorem.

share|cite|improve this answer

Your Answer


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

Not the answer you're looking for? Browse other questions tagged or ask your own question.