Angles in a circle rules
- how to find angles in a circle
- how to find angles in a circle with arcs
- how to find angles in a circle with tangent
- how to find angles in a circle calculator
How many angles in a circle
Find angle in circle calculator...
Circle Theorems
Some interesting things about angles and circles
Inscribed Angle
First off, a definition:
Inscribed Angle: an angle made from points sitting on the circle's circumference.
A and C are "end points"
B is the "apex point"
Play with it here:
images/circle-prop.js?mode=inscribe
When you move point "B", what happens to the angle?
Inscribed Angle Theorems
Keeping the end points fixed ...
...
the angle a° is always the same,
no matter where it is on the same arc between end points:
(Called the Angles Subtended by Same Arc Theorem)
And an inscribed angle a° is half of the central angle 2a°
(Called the Angle at the Center Theorem)
Try it here (not always exact due to rounding):
images/circle-prop.js?mode=inscribe2
Example: What is the size of Angle POQ?
(O is circle's center)
Angle POQ = 2 × Angle PRQ = 2 × 62° = 124°
Example: What is the size of Angle CBX?
Angle ADB = 32° also equals Angle ACB.
And Angle ACB also equals Angle XCB.
So in triangle BXC we know Angle BXC = 85°, and Angle XCB = 32°
Now use angles of a t
- how to find angle in a circle graph
- how to calculate angles in a circle