1. Trigonometry - Intro
Ms. Mougharbel

2. Definitions
Radian: a unit of angle, equal to an angle at the center of a circle whose arc is equal in length to the radius
Degree: a unit of measurement of angles, one three-hundred-and-sixtieth of the circumference of a circle.
Arc Length: The distance along the arc (part of the circumference of a circle, or of any curve).
Sector Area: The part of a circle enclosed by two radii of a circle and their intercepted arc. A pie-shaped part of a circle

3. Unit Circle

4. Formulas Radian  Degree = Radians(180/)
Degree  Radian = Degrees(/180)
Area of a sector: 𝐴= 𝐴𝑟𝑐 𝐷𝑒𝑔𝑟𝑒𝑒 360 (𝜋 𝑟 2 )
Length of an arc: 𝐿= 𝐴𝑟𝑐 𝐷𝑒𝑔𝑟𝑒𝑒 360 (2𝜋𝑟)
For a circle: 
Arc Length = θ × r. (when θ is in radians) 
Arc Length = (θ × π/180) × r.