1. Find the value of Sin^-1(-1/2)

Question

1. Find the value of Sin^-1(-1/2)
     a. -30 degrees
     b. 30 degrees
     c. 150 degrees
     d. 330 degrees

2. Find the exact value of cos(-420 degrees)
      a. -1/2
      b. 1/2
      c. sqrt of 3/2
      d. -sqrt of 3/2

3. p(-9/41, 40/41) is located on the unit circle. Find sin theta.
      a. 40/41
      b. -9/41
      c. -9/40
      d. -40/9

4. In triangle ABC, C = 60 degrees, a=12, and b=5. Find c.

5. Which triangle should be solved by beginning with the law of Cosines?
       a. A=115 degrees, a=19, b=13
       b. A=62 degrees, B=15 degrees, b=10
       c. B=48 degrees, a=22, b=5
       d. A=50 degrees, b=20, c=18

drwls · Answer

1. Both a and d are correct. -30 and 330 degrees are the same angle

2. d

3. b theta = sin^-1 (-9/41)/1, siunce it is on a unit circle.
Note that sqrt[(-9/41)^2 + (40/41)^2] = 1

4. Use the law of cosines when you know two adjacent sides and the included angle (which would have a capital letter designation different from the sides). Only one of the choices fits this criterion.