Answer:

Step-by-step explanation:
Start by drawing out the triangle on the graph:
(See picture)
(By the drawing you can judge me that I am a really bad artist)
Theta and the side lengths are labeled, the hypotenuse has a length of √21 by Pythagora's theorem. Now, time to put everything to the trigonometric functions:

(Suppose that x is theta as I can't type it)
By some basic understanding that's all that I can do.
Slope of 4 means you add 4 to the y and 1 to the x so the answer is (-1,9)
While it was true that the cotton gin reduced the labor of removing seeds, it did not reduce the need for slaves to grow and pick the cotton. In fact, the opposite occurred. Cotton growing became so profitable for the planters that it greatly increased their demand for both land and slave labor