Trigonometry doesn’t begin with formulas. It begins with a right triangle. In this video, we break down sine and cosine starting from the most basic geometric idea: an angle inside a triangle and the three sides that respond to it. From that single angle, the triangle assigns roles. One side stands opposite the angle. Another rests adjacent to it. And the longest side, the hypotenuse, connects everything. Sine measures how much the triangle rises vertically compared to its total length. Cosine m