Trig Ch.1-2

• 1 degree = 60 minutes
• 1 minute = 60 seconds
• 72.18 degrees to DMS

  • .18(60') = 10.8'
  • .8(60'') = 48"
  • =72 degrees 10' 48''
• 25 degree 15' 20'' to DD

  • 20''/60'' = .33'
  • 15.33'/60' = 2.56 degrees
  • = 25.256 degrees
• sin = opposite leg / hypotenuse
• cos = adjacent leg / hypotenuse
• tan = opposite leg / adjacent leg
• csc = hypotenuse / opposite leg
• sec = hypotenuse / adjacent leg
• cot = adjacent leg / opposite leg
• in an isosceles right triangle:

  • if the legs are equal to 1
  • then the hypotenuse will be equal to the square root of 2
• in a right triangle with angles of 30, 60, 90:

  • the side opposite of 30 will be equal to 1
  • the side opposite of 60 will be equal to square root of 3
  • the side opposite of 90 will be equal to 2
• • csc = 1/sin(#)
  • sec = 1/cos(#)
  • cot = 1/tan(#)
• tan B = 2

  • tan^-1 (2) = B
• coterminal angles: angles with the same initial and terminal sides but different amounts of rotation

  • 135, 495, -225
  • -30, -390, 330
• $x^2 +$$y^2 =$$r^2$

  • x = adjacent
  • y = opposite
  • r = hypotenuse
• 1/0 = undefined
• reference angle: the positive acute angle made by the terminal side of angle and the x-axis

  • 294 degrees = 360 - 294 = 66 degree reference angle
• find angles in intervals [0,360)

  sin = 0.52991926

  • sin^-1 (#) = 32
  • 180-32 = 148
  • Answers: 32, 148

  tan = -0.70020753

  • tan^-1 (#) = -35 ; -35 not in intervals
  • 360 - 35 = 325
  • 180 - 35 = 145
  • Answers: 145, 325