/en/tags/3d-basics/Recent content in 3d-Basics on Feynman's BlogHugoen-USSun, 05 Jul 2026 10:00:00 +0800/en/posts/trigonometry-guide/Sun, 05 Jul 2026 10:00:00 +0800/en/posts/trigonometry-guide/<blockquote class="blockquote-regular"> <p>Trigonometric functions are the core tool for describing periodic phenomena and the mathematical foundation for 3D graphics. This article starts from right triangles and systematically reviews the definitions, formulas, graphs, and inverse trigonometric functions.</p> </blockquote> <h2 id="01-basic-definitions">01 Basic Definitions</h2> <h3 id="right-triangle-definition">Right Triangle Definition</h3> <p>In a right triangle, let angle $\theta$ be an acute angle:</p> <ul> <li><strong>Sine</strong> (sin): $\sin\theta = \frac{\text{opposite}}{\text{hypotenuse}}$</li> <li><strong>Cosine</strong> (cos): $\cos\theta = \frac{\text{adjacent}}{\text{hypotenuse}}$</li> <li><strong>Tangent</strong> (tan): $\tan\theta = \frac{\text{opposite}}{\text{adjacent}} = \frac{\sin\theta}{\cos\theta}$</li> </ul> <h3 id="opposite-adjacent-hypotenuse-computation-formulas">Opposite, Adjacent, Hypotenuse Computation Formulas</h3> <p>Given a trigonometric function value and one side, the other sides can be found:</p>