1, basic formula: sinα= opposite side length/hypotenuse length cosα= adjacent side length/hypotenuse length tanα= opposite side length/adjacent side length multiple angle formula: sin2α=2sinαcosαcos2α=cos? (α)-Sin? (α)tan2α=2tanα/ 1-tan？ α。

2. Half-angle formula: sin α/2 = √ 1-cos α/2, cos α/2 = √ 1+cos α/2, tan α/2 = √1-cos α/65438+sin. α/2、cosα= 1-tan？ α/2/ 1+tan？ α/2、tanα=2tanα/2/ 1-tan？ α/2。

The meaning of the formula

1. formula is a mathematical expression or physical model, which is usually used to describe the relationship between quantities or natural phenomena. They are an indispensable part of mathematics and science, which can make us have a deeper understanding of complex problems.

2. Formulas usually express complex concepts or relationships in a concise and clear way. For example, Euler formula E I π+ 1 = 0 expresses the relationship between complex unit and zero. Although this formula is simple, it has far-reaching significance and reveals the basic properties of complex number fields.

3. Formulas can provide an in-depth understanding of phenomena. For example, Newton's second law of motion, F=ma, describes the relationship among force, mass and acceleration. This formula not only helps us to understand the law of motion of objects, but also provides a basis for us to design and manufacture machines.

4. Formulas can also help us to predict and solve problems. For example, Newton's law of universal gravitation F=G(m 1m2/r? ), which describes how the gravity between two objects depends on their mass and distance. This formula can be used to predict the motion of celestial bodies and even help us design the moon landing plan.