The sector has an axis of symmetry.
1. Axis of symmetry
1. Definition of axis of symmetry
The axis of symmetry refers to the straight line that makes the geometric figure form axial symmetry or rotational symmetry, and is a part of the symmetric figure After rotating a certain angle around it, it coincides with another part. For example, ellipses and hyperbolas have two axes of symmetry, and parabolas have one. The axis of symmetry of a right cone or right cylinder is a straight line passing through the center of the base and the vertex or the center of another base.
2. Axisymmetric graphics
Common symmetrical graphics include axisymmetric graphics. When a graphic is folded in half along a straight line, the two parts completely overlap. Such graphics are called axisymmetric graphics. Line segments, angles, isosceles triangles, equilateral triangles, rhombuses, rectangles, squares, isosceles trapezoids, circles, etc. are all axially symmetrical figures.
2. Sector
1. The axis of symmetry of the sector
The sector has an axis of symmetry. The sector is a part of a circle and folds along the straight line of its radius. , the two sides will completely overlap.
2. Definition of fan shape
The figure enclosed by an arc and two radii passing through both ends of the arc is called a fan shape (the combination of a semicircle and a diameter is also a fan shape). Obviously, it is bounded by a part of the circumference and its corresponding central angle. "Elements of Geometry" defines a sector as follows: a figure surrounded by two sides of an angle whose vertex is at the center of a circle and an arc cut by these two sides.
3. Folding fan
In ancient times, scholars and literati generally used folding fans. Folding fans were generally used by scholars and literati. They had bamboo fan ribs and paper fans. Decorating it with some calligraphy and painting by hand can show off your calligraphy or painting skills, as well as your own taste. The shape of this kind of fan is fan-shaped.
Fan shape in life
1. Folding fan. The folding fan is a very practical fan-shaped item that can not only be used to fan the air, but can also be used as a decoration.
2. Scallops. The scallop is a sea creature with a very beautiful fan-shaped shell.
3. Round fan. Tuanfan is a traditional Chinese fan, mostly round or oval in shape, often used in paintings or as gifts.
4. Ginkgo leaves. Ginkgo leaves are shaped like a fan and are very beautiful. They are often used to make bookmarks or as decorations.
5. Sector-shaped plate hoe. In agricultural production, there is a type of hoe that is fan-shaped, which can better adapt to the needs of farming.
6. Peacock’s tail. The fan-shaped tail of a peacock is very beautiful and is one of the most striking features of a peacock.