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Class 6 (Old)

Course: Class 6 (Old)>Unit 9

Lesson 6: Three dimensional shapes

Recognizing common 3D shapes

Learn about 3D shapes! A square pyramid has a square base. A rectangular prism is a box shape with all rectangular sides. A triangular prism has triangle faces on opposite sides. A sphere is like a globe. A cylinder looks like a can with circular faces on top and bottom. Shapes are fun!

Want to join the conversation?

• what is a vertice?
• A vertex (vertices is the plural of vertex) is a point where the sides of a shape intersect. So basically any corner on a shape is a vertex.
• how do i find surface area
• You find the area of each side of the object and then add them all together.
• Would a shape with an octagon for a base and triangles for sides meeting at a point be called an octagonal pyramid?
• Yes,an octagonal pyramid is a pyramid with a base that's a polygon with eight sides, or an octagon, and triangular faces, or sides, that meet at a point directly above the bottom.
• What kind of polygon have 100 sides ?
• Think of a century as 100 years, so it would be a centagon. This is like a decagon is like a decade (10 years).
• A sphere is a circle right?
• It may seem that way, but technically, a sphere is a 3-D shape (has width, height, and depth) and a circle is 2-D (width and height) A circle is missing the depth needed to become a 3-D shape. Also, you find volume for spheres and area for circles. This then changes the formulas.
Circle: A = pi*r^2
Sphere: V = 4/3*pi*r^3
Good luck in your journey through geometry!
• The Rectangular prism is also called a Cuboid. True or False?
• That is true. A rectangular prism is also called a cuboid. A cuboid is a three-dimensional shape that has six faces, all of which are rectangles. A cuboid is also a right prism, which means that its bases are parallel and congruent, and its lateral faces are perpendicular to the bases. A cube is a special case of a cuboid, where all the faces are squares. However, not all rectangular prisms are cuboids. A rectangular prism can also be oblique, which means that its bases are not aligned one directly above the other, and its lateral faces are parallelograms2
• At , Sal says "This has sides that are triangles", doesn't he mean faces?
• I think he means bases.