What is the best angle to lean a ladder against a wall?

If you are asking, what's the distance (x) from the bottom of the ladder to the wall, then... x squared + 2 squared = 3 squared x squared + 4 = 9 x squared = 5 x = the square root of 5, or approx...

If the wall is straight and the ground level then this is an outline of a right angle-triangle. If the top of the ladder makes an angle of 530 with the wall then the bottom of the ladder must make...

10 sin71 = 10 x 0.9455 = 9.455 feet (just under 9' 5½")

15*cos(60) = 7.57.5 m

The ladder is being used as a ramp.Or just as a ladder.