Video narration
How can a ladder's tilt tell you how high it reaches? The ladder, wall, and ground make a right triangle, with one square corner. The angle is more than a tilt: it fixes the ratio, how the sides compare. But the angle alone doesn't give you the actual height. Measure a side, like the ladder's length, and trigonometry uses it with the angle to work out the height. The ladder's angle plus one measured length tells you how high it reaches.