The formula of the circle and arc of each inner corner of a regular N polygon is equal to (n-2) × 180/N Arc length calculation formula: L=n R/ 180 Sector area formula: S sector =n R 2/360 = LR/2 Internal common tangent length =d-(R-r
Two circles are circumscribed by D > R+R. Two circles are circumscribed by D = R+R. Two circles intersect R-R < D < R+R (R > R). Two circles contain D < R-RR > R theorem. The intersection line of two circles bisects the common chord of two circles vertically. Theorem divides the circle into n (n ≥ 3): (1) The polygon obtained by connecting the points in turn is the inscribed regular N polygon of the circle; (1) The tangent of a circle passing through a point, and the polygon whose vertex is the intersection of adjacent tangents is the circumscribed regular N polygon of the circle.
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In ancient China, mathematics was called arithmetic, also called arithmetic, and finally it was changed to mathematics. Arithmetic in ancient China was one of the six arts.
Mathematics originated from the early production activities of human beings, and the ancient Babylonians had accumulated some mathematical knowledge, which could be applied to practical problems. As far as mathematics itself is concerned, their mathematical knowledge is only obtained through observation and experience, and there is no comprehensive conclusion and proof, but their contribution to mathematics should also be fully affirmed.
The knowledge and application of basic mathematics is an indispensable part of individual and group life. The refinement of its basic concepts can be found in ancient mathematical documents of ancient Egypt, Mesopotamia and ancient India. Since then, its development has continued to make small progress. But algebra and geometry at that time were still independent for a long time.
Algebra can be said to be the most widely accepted "mathematics". It can be said that the first mathematics he came into contact with was algebra since everyone began to learn to count when he was a child. Mathematics is a subject that studies numbers, and algebra is also one of the most important parts of mathematics. Geometry is the earliest branch of mathematics studied by people.
Until the Renaissance in16th century, Descartes founded analytic geometry, which linked algebra and geometry which were completely separated at that time. From then on, we can finally prove the theorem of geometry through calculation; At the same time, abstract algebraic equations and trigonometric functions can also be graphically represented. Then more subtle calculus was developed.