1a) For the first problem what you did was to first find an approximation of the anwer in degrees and then you convereted that approximation to minutes, and then to seconds. But what I think they want is a more exact conversion expresed in degrees, minutes, and seconds:
So it's 120 degrees PLUS a bit more, and you need now to convert the remainder to minutes, then seconds:
Now convert this remainder of this to seconds:
which rounds to 16".
So you have: .
1b) To find the sine you can use a calculator, but it's very close to .
2) Your answers of and are good, but the other two answer are in the wrong quadrants - they have sine of +1/2. You can either add or subtract a multiple of 2 to your first two answers.