Flashcards: Trigonometry Essentials — 11 cards

What is the radius of the unit circle centered at the origin?

The radius is 1.

Unit circle radius

Radius is 1, circumference is 2π.

What is the positive direction on the trigonometric circle?

Counterclockwise is the positive direction.

Radian-degree relation

π radians = 180°.

What does a radian measure on the unit circle?

An arc length on the unit circle.

Coterminal angles

x + 2kπ, k in integers.

What is the conversion relation between radians and degrees?

$\pi\text{ radians}=180^\circ$.

Principal measure interval

Angles in [-π, π].

Sine on circle

Vertical coordinate of point.

Cosine on circle

Horizontal coordinate of point.

Arc length of half-turn

π radians.