1, the circle is a regular plane geometry figure, and the area of the circle refers to the size of the plane space occupied by the circle. S is often used to express the solution method of the circle. There are many calculation methods, and Kepler solution is the most commonly used one. Zu Chongzhi, an ancient mathematician in cavalli, started with a regular hexagon inscribed in a circle, multiplied by the number of sides, and approximated the area of a circle with the inscribed area of a regular polygon.
2. Kepler,/kloc-a German astronomer in the 6th century, divided the circle into many small sectors; The difference is that he divided the circle into infinitely many small sectors from the beginning. The area of a circle is equal to the sum of the areas of an infinite number of small sectors, so in the last formula, the sum of the areas of small arcs is the circumference of the circle, so there is S=πr? .
3. Mathematicians in ancient India cut the circle into many small petals similar to watermelon, then butted these small petals into a rectangle, and replaced the area of the circle with the area of the rectangle. Mathematicians in ancient Greece started with regular polygons inscribed in a circle and circumscribed at the same time, increasing the number of their sides and approaching the area of the circle from the inside out.