Two birds sit at the top of two different trees. the distance between the first bird and a bird-watcher on the ground is 14.1 feet. the distance between the bird-watcher and the second bird is 27.9 feet. what is the angle measure, or angle of depression, between this bird and the bird-watcher?

27.9 is the hypotenuse 14.1 is the opposite
30.4
59.6
63.2
87.9

Use the trig ratio which gives you the most information. Here we have opposite and hypotenuse relative to angle x, so think sin( x ) = 14.1 / 27.9

Now we want to solve for x, but x is stuck inside the sine function
So how do we do this?
We can 'undo' the sine function by using the inverse sine. apply the inverse sin to both sides of the equation.
sin^-1 ( sin(x) )  =  sin^-1 ( 14.1 / 27.9)
The left side 'cancels' , leaving you with x 
x = sin^-1 ( 14.1 / 27.9)
Now you need a calculator.
Make sure you are in degree mode.
Calculators can give you answer in radian or degree.
If you get a decimal answer, you are probably in radian mode. 
Round up if you want nearest hundredth
30.3563 ≈ 30.36
Or you can round to the nearest tenth
30.36 ≈ 30.4
Hope this helps! :)