Video narration
How can you measure a ladder's height on a wall when you cannot measure it directly? Picture a ladder leaning against a wall. The wall and ground meet at a right angle, so the ladder, wall, and ground form a right triangle. Now look at the angle where the ladder meets the ground. It is more than a corner. Its size becomes a number describing how the sides relate. If you know one side, choose the ratio that matches the sides you need. Sine compares the side opposite the angle with the sloping side, the hypotenuse. Cosine compares the nearby, adjacent side with the hypotenuse. Tangent compares opposite with adjacent. With the ladder's angle and one measured length, the right ratio gives the missing height or distance. So, how does trigonometry do it? It turns an angle and one known side into the missing length.