You will need
- Ruler, pencil, eraser.
Ball is a special case of the simplest three-dimensional figure. Through it, you can spend an infinite amount of sections, and any of them would be around. This happens regardless of how close the section is to the center of the ball. To calculate the area of the resulting cross-section is the easiest in that case, if it is carried out through the center of a ball whose radius is known. In this case, the area of the cross section is equal to:S=NR^2.
The other figure, the area of the cross section which you want to find in geometry problems is a parallelepiped. It has edges, and faces. Face is one of the planes of a parallelepiped (cube), and rib - side. The parallelepiped whose edges and faces are equal is called a cube. All sections of the cube squares. Knowing this property, calculate the area of cross-section-square:S=a^2, where a is the edge of the cube and the side section.
If the conditions of the problem given a regular parallelepiped, in which all faces are different, the cross section can be a square and a rectangle with different sides. The cross section drawn parallel to the two square faces is a square, and the cross section drawn parallel to two rectangular - rectangle. If the section passes through the diagonal of the parallelepiped, it is also a rectangle.
The area of the square cross-section parallelepiped can be found using the same formula as for a cross-section of the cube. If the cross section of the parallelepiped is a rectangle, find it, knowing two parameters, the length and width of the two rectangular faces:S=a*b, where a is the edge length, b -width of the verge.Diagonal cross section of a parallelepiped find by multiplying the diagonal of the bottom base to the height of the parallelepiped:S=d*h where d is the diagonal of the base, h is the height of the base.
Cone - one of the figures of rotation, the cross section of which can have different form. If you cut the cone parallel to the lower base section is a circle and if we draw a parallel section in half through the top of the cone, you get a triangle. In other cases, sectionmi will be a trapezoidal shape.If the cross section is a circle, calculate its area according to the following formula:S=NR^2.Square cross-section, which is a triangle is equal to the product of half the base to the height:S=1/2f*h , where f is the base of the triangle, h is the height of the triangle.