14.3 Trigonometric Functions

Concerned with angles and their measurements

• (sin , cos ) coordinates on unit circle
• cos = sin( + /2)

  

• Law of sines:

  

• Law of cosines: a² = b² + c² - 2bc cos A

  Proof.

  a2	=	b2 - (b cos A)2 + (a cos B)2
  a cos B	=	c - b cos A

• Exercises:
  1. Given 2 angles and a side of a triangle, find the remaining sides
  2. Given 2 sides and an angle of a triangle, find the remaining sides and angle