A Google or Bing search box can be your friend, if you don't have a calculator with inverse trig functions. Most calculators that have trig functions also have the inverse functions, usually after a 2nd or "shift" key. Often, there is a mode setting for degrees or radians.
arcsin(0.33) ≈ 19°
arccos(0.47) ≈ 62°
arctan(1.21) ≈ 50°
arcsin(0.82) ≈ 55°
There are many ways you can write a ratio. They're all basically the same thing, though. 5:9, 5 to 9, and 5/9 (which is a fraction) are all just different ways to write ratios.
We can find the slope of this line by using the slope formula:

We'll use the points (-6, 0) and (0, -3)
(-3 - 0) / (0 + 6) = -3/6 = -0.5
The slope of the line is A, -1/2
Blue and green but i also like black
12x12 + 12x12 = 288 = root of 288= 16.97