It should be D, I did the math :)
Answer:

Step-by-step explanation:
The distance between two points
and
can be calculated as

Then the distance between points
and
is

Answer:
The formula for period is T = 1 / f , where "T" is period – the time it takes for one cycle to complete, and "f" is frequency.
To get period from frequency, first convert frequency from Hertz to 1/s.
Now divide 1 by the frequency. The result will be time (period) expressed in seconds.
Answer: (-4, -7)
I dont know how to explain how I got that but I recommend using an app called Desmos. :)
Two angle that form a linear pair are supplementary meaning they add to equal 180° (straight line).
make the bigger angle = x
then smaller angle = x - 30°
x + x - 30 = 180
2x - 30 = 180
2x = 180 + 30
2x = 210
x = 210/2
x = 105
The question is to find the smaller angle which was: x - 30
105 - 30 = 75°