basic trigonometry

--> Basic trigonometry problems deal with functions problems. In trigonometry angles plays a major role to learn the test answers. These angles are mainly used to relate the side length of the triangles. The most important functions in trigonometry are sine, cosine, and tangent. The sine function is takes an angle and tells the length of the y-component is rise of that triangle. The cosine function is takes an angle and tells the length of x-component of a triangle. The tangent function is takes an angle and tells the slope.

Basic trigonometry problems are solved with detailed solutions.

Find the value of cos (- 390 ^o).
Solution:

• We apply the identity cos(-x) = cos(x) to write
  
  cos (- 390 ^o) = cos (390 ^o)
• While 390 degrees is greater than 360 degrees, we find a co terminal angle t, greater than zero and less than 360 degrees, to 390 degrees.
  
  t = 390 - (360) = 30 ^o
• while 390 degrees and angle t = 30 are co terminal, we can write
  
  cos (390 ^o) = cos ( 30 ^o )

• Finally.
  
  cos(- 330 ^o) = cos ( 330 ^o )
  
  = cos (30) = sqrt (3) / 2

-->