Cleo is looking at an airplane flying at an altitude of 3 miles. Her angle of elevation is 37 degrees. About how far is the land distance from Cleo to the plane?

Think of a right triangle, with 3 miles being the length of the vertical leg and x the length of the horiz. leg.  Then tan 37 deg = opp / adj, or

tan 37 deg = 3 mi  /  adj, so that   adj = (3 mi) / (tan 37 deg) = (3 mi)(0.754)
                                                                                                = 2.26 miles