1, number-shape combination method: For some relatively simple shapes, such as triangles and quadrangles, the number of angles in the shapes can be directly counted. This method is usually suitable for basic geometric problems.
2. Classification discussion method: For some complicated geometric figures, we can discuss them according to different classification methods (for example, according to the size of the angle and the type of the figure, etc.). ) and count the angles in the picture one by one. This method requires some mathematical thinking and skills.
3. Using formula method: For some specific geometric figures, such as polygons and solid figures, the number of angles can be calculated by using some specific formulas. This method needs to master some geometric formulas and theorems.
4. Program calculation method: If you are solving some complex geometric problems, such as polyhedrons and lines with different planes, you can calculate the number of angles by writing a program. This method requires some programming skills and mathematical knowledge.
5. Using space coordinate system method: In analytic geometry, space coordinate system is usually used to represent geometric elements such as points, lines and surfaces. Therefore, by establishing the spatial coordinate system, the geometric problem can be transformed into an algebraic problem, so it is easier to calculate the number of angles.
There are several ways to check the angle:
1. formula method: for any n-polygon, the formula of the sum of its internal angles is (n-2) × 180. Therefore, according to this formula, the number of angles of the N-polygon can be easily calculated.
2. Law method: According to the position and quantity of corner points in different figures, some laws can be summarized. For example, in a triangle, any three vertices can form a triangle, so any triangle has three angles; In a quadrilateral, any two diagonal lines can form a quadrilateral, so any quadrilateral has four corners. By analogy, you can easily find the number of angles according to the law.
3. Counting method: For relatively simple graphics, you can check the number of angles by manual counting. For example, in a triangle or a square, the number of angles can be determined by directly calculating the number of intersection points on the sides.
4. Geometric attribute method: You can use the geometric attribute of the angle to check the angle. For example, we can solve the numerical value of the angle through the symmetry of the angle. If the complementary angle of an angle is known, then we can use the properties of the complementary angle to solve the numerical value of the unknown angle. Complementary angle means that the sum of two angles is equal to 90 degrees. So we can solve the value of unknown angle by the sum of complementary angle and known angle.
5. Vector method: In three-dimensional space, you can use the concept of vector to check the angle. By calculating the dot product of two vectors, the included angle between the two vectors can be obtained. Therefore, by calculating the included angles between all vectors, the degrees of all angles can be obtained.