Relationship of Linear Velocity and Angular Velocity

v=rw
(s/t)=r(θ/t)

Angular Velocity

Angular velocity measures how fast an angle is changing.
w = angle in radians / time => θ/t

Linear Velocity

Linear velocity measures how fast an object is going.
Velocity = arc length / time:
v=s/t

Area of a Sector of a Circle

The area K of a sector (a slice of pie) of a circle with radius r and angle θ is:
k=1/2(r²θ)

*If you are given the angle in degrees, remember to convert to radians

Formula for Circles

Formula of a circle:
X²+Y²=r²

Circumference of circle:
2Πr

Setting radius to 1 (one unit) results in:
X²+Y²=1²
2Π

Length of Arc

The portion of the perimeter of a circle of a section indicated by an angle θ has a length :
s = rθ

where s is the length in same units r is given