2-1/4
2/1=8/4 Multiply top and bottom by 4
8/4-1/4
7/4
1 3/4
Written as a power of ten is 256.×10^0 or 2.56×10^1
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°
Corresponding angles are angles that are equal in degrees and in this case it is <8 and <4 but there is also <5 and<7.