1. pyramids

2. Pyramids
There is a square at the bottom, four triangles around it and a vertex on top. At the bottom we have a rectangle. a triangle or some other polygon in the place of the square, such solids are called pyramids.

3. SOME PYRAMIDS

4. A pyramid with square base is called square pyramid.

5. Rectangular pyramid
A pyramid with rectangular base are called rectangular pyramid.

6. Triangular pyramid
A pyramid with triangular base are called triangular pyramid.

7. points The lateral faces of a pyramid are isosceles triangle.
Sides of the figure forming the base of the pyramid are called its base edges.
Other sides of the triangles are its lateral edges.
The top end is the apex of the pyramid.
Perpendicular distance to base from its apex is the height of the pyramids.

9. areas
Surface area of a pyramid is the sum of the area of its base and areas of its four lateral faces that are triangles.

10. volume
Volume of a square pyramid is a third of the product of its base area and height.
Volume of a square pyramid = 1/3*base area*height.

11. cones
A pyramid with a circular base is called cone

12. Distance between center of base circle and apex of cone is the height of cone.
There is a right angled triangle with slant height of cone as hypotenuse , base radius and height as perpendicular sides.

13. volume SURFACE AREA Volume of a cone = 1/3+base area +height.
Surface area of a cone = base area+ curved surface area
=𝜋 𝑟 2 +𝜋𝑟𝑙

14. sphere
Ball is a solid in the shape of a sphere.

15. There is a center for a sphere.
Distance from the Centre of a sphere to any point on the sphere is its radius.
Two time radius is diameter.
A solid sphere can cut in to two equal parts .
The center,radius,diameter of the hemisphere is same as the sphere.

16. Surface area of a sphere of radius ‘r’ =4𝜋 𝑟 2 .
Volume of a sphere = 4 3 𝜋 𝑟 2 .
Surface area of a hemisphere = 3𝜋 𝑟 2 .
Volume of a hemisphere = 2 3 𝜋 𝑟 2 .