A regular pentagon and a circle through two of its vertices and its centre. What’s the angle α?

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## Solution

The angle α is 36°.

geometry puzzles

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- Post author By Rik D. Tangerman
- Post date February 1, 2023
- 1 Comment on Getting stuck

A regular pentagon and a circle through two of its vertices and its centre. What’s the angle α?

Scroll down for a solution to this problem.

The angle α is 36°.

## One reply on “Getting stuck”

Looking at the angles of pentagon and pentagram gives the solution directly.

There is a second solution (point G in the second figure above).