An airplane is descending 225 feet per 1000 feet of horizontal distance covered. What is the cosine of the angle that its path of descents makes with the horizontal.

Answer 1

slope of a line is the tangent of the angle that the line makes with the horizontal,
so slope = rise/run = 225/1000 = 9/40
so the hypotenuse of the corresponding triangle is
√(40^2 + 9^2) = √1681

cosine (angle) = 40/√1681 = 40/41