CIRCLES!

An arc is when you have 2 points on a circle and you figure out the degree measure of them.

For example, If the perimeter of the circle is 120 units and arc AB is 30 units long, then 30 / 120= 0.25. Then you can multiply 0.25 * 360 degrees, which gives you 90.

A

B

B

Angle ACB = (Arc AB) / 2

A

C

B

D

Angle AEB = Angle DEC = [ (Arc AB) + (Arc CD) ] / 2

E

A

C

B

Z

Angle Z = { (Arc A) - (Arc B) } / 2

A

Angle (ZAB) = { Arc (AB) - Arc (BC) } / 2

Z

A

B