Inscribed angleCircle angle given
The angle on the circle is given. Find the angle at the center.
When the angle on the circle is given, the angle at the center is twice as big. These free printable worksheets ask for that one direction, eight times a page: a 65° angle on the circle stands on the same arc as a 130° angle at the center.
If they get stuck

The answer key prints on a separate page.
Each circle has two angles standing on the same arc. The one on the circle carries a number, and the one at the center carries a question mark. The question is the reverse of the more common one, and that is why it gets its own page. A student who has only ever halved will halve here as well, and 65° turns into 32.5° on the paper.
A decimal like that is a useful warning, because every answer here is a whole number. The central angle is also the bigger of the pair, and it should look bigger. Asking which angle looks wider before doing any arithmetic is a quick habit that catches this mistake.
Circle angle 15°, find the angle at the center