The biggest problem people have is knowing what function to use in right triangle trigonometry.
So, here's a little trick my teacher taught me when learning what function to use.
It's an abbreviation, but sounds like some Indian princess, right? That's what makes it easy to remember.
SOH-CAH-TOA
Sine= opposite/hypotenuse
Cosine= adjacent/hypotenuse
Tangent= opposite/adjacent
To find side a you need to figure out how 'a' and the side given relates to the angle.
So how does 3,250 ft relate to 42°?
It's the hypotenuse.
(Which is the longest side in the triangle, opposite the 90° angle.)
How does side a relate to 42°?
It's adjacent to the angle.
So...
We must use cosine, because we have adjacent and the hypotenuse.
Your equation will look like this:
Cos42°= a/3,250
Now you need to get 'a' by itself, and this takes some simple algebra skills.
To get 'a' by itself you need to multiply the 3,250 from the right side. So to keep the equation balanced you have to multiply the 3,250 onto the left side.
This will get you:
3,250cos42°= a
Now plug that into your calculator and you have your answer.
We will use the same process to find side b.
Since we know 3,250 is the hypotenuse, we need to find how 'b' relates to 42°.
B is opposite the angle.
We have opposite and the hypotenuse, so we will use the function sine.
Sin42°= b/3,250
We will use the same trick as before and get ourselves:
3,250sin42°= b
Hope that helps! :)