Inscribed angle in a circle worksheets

Two angles standing on the same arc: one at the center of the circle, one out on the rim. The one at the center is always twice the other. These free printable worksheets ask for each direction, and mix them.

Inscribed angle in a circle
Inscribed angle in a circle worksheet — Center angle or circle angle, free printable with answer key

The answer key prints on a separate page.

What's on this sheet

This is a theorem rather than a formula, and the difference shows in what a child has to do. There is nothing to measure and nothing to substitute — the whole question is reading which of the two marked angles was given, and then halving or doubling. Which is exactly why a page of one direction is not enough practice: handed the center angle the mistake is doubling, handed the rim angle it is halving, and the mixed page is the one where the figure has to be read first.

Why this sheet works

Both angles are marked on every figure, one with its size and one with a question mark, because the theorem is a statement about a pair. A figure showing one angle would be showing half the question, and the two arcs are drawn at different radii so a 30° angle and a 150° one do not read the same at a glance.