This is because of King Henry Died by Drinking Chocolate Milk (Kilometers,Hectometers, Decameters, Base(Liters,Meters, and Grams) Decimeters, Centimeters and Millimeters). So when you have 50 milliliters, milliliters is one place away from centiliters so you move the decimal forward one place.
Ok the ladder and the ground will make a right triangle/right angle. This is because the ground is flat, the wall is straight and only the ladder is leaning/slanted. I hope this helps.
