Let's consider a circle with center O and a chord AB. Draw the line segment connecting the center O to the midpoint of the chord AB.
Let's consider a circle with center O and a tangent line AB. Draw the radius OC that intersects the tangent line at the point of tangency C.
3.To prove this theorem, we can consider a sphere with radius r and divide its surface into small, approximately rectangular elements. The area of each element is approximately equal to the product of the lengths of its sides, which are both approximately equal to the radius r.
4.To prove this theorem, we can consider a sphere with radius r and divide it into thin, concentric spherical shells. The volume of each shell is approximately equal to the product of the surface area of the shell and its thickness, which is infinitesimally small.