UNIT CIRCLE, SIN, COS, SECTOR VOCAB REVIEW

revolution

revolution

a common unit for measuring very large angles; 1 revolution is a complete circular motion

degree

a common unit for measuring smaller angles; 1 revolution = 360°

radian measure

another way to measure small angles

angle in standard position

has a vertex at the origin and the initial ray lies on the positive x-axis

quadrantal angles

where the circle intersects the x and y-axis

coterminal angles

two angles in standard position that have the same terminal ray

sector

the region bounded by the central angle and the intercepted arc

arc length

a fraction of the circumference

reference angles

angles in different quadrants that have the same trig ratios [although the signs may be different]

initial ray

the starting ray

terminal ray

the ray created after moving by θ

arc length in radian

s=θr

arc length in degrees

s=(θ/180°)πr

area of a sector w/radians

k=½θr²

area of a sector w/degrees

k=(θ/360°)πr²

area of a sector w/arc length & radius

k=½sr

sinθ

y; y/r

cosθ

x; x/r

equation of unit circle

x² + y² = r²

degree to radians

___° × (π/180°)

radians to degrees

___ rad × (180°/π)