Solid Figures Volume and Surface Area Lets review

Solid Figures: Volume and Surface Area

Let’s review some basic solid figures…

Sphere A sphere is a ball. l It has no faces, edges, or vertices. l

Cube A cube is like a box. l It has six faces, six edges, and four vertices. l All of a cube’s faces and edges are equal. l

Rectangular Prism A rectangular prism is also like a box. l It has six faces, six edges, and four vertices. l All of its faces are either squares or rectangles. l

Cylinder A cylinder is like a soup can. l It has two circular faces on each end, but no edges or vertices. l You could say that a cylinder is a “circular prism. ” l

Finding Volume l We’re going to talk about how to find the volume of rectangular prisms and cylinders.

Volume: Rectangular Prisms l The formula for finding the volume of a rectangular prism is volume = length x width x height, or V = l x w x h.

Volume: Rectangular Prisms l Suppose you have a rectangular prism that is 9 inches long, 6 inches wide, and 5 inches high. l What is the volume of this rectangular prism? l. V=9 x 6 x 5 l V = 270 cubic inches

Volume: Cylinders l The formula for finding the volume of a cylinder is pi x radius squared x height.

Volume: Cylinders l Suppose you have a cylinder with a height of 8 centimeters and a radius of 12 centimeters. l What is the volume of this cylinder? l V = 3. 14 x (8)^2 x 12 l V = 2, 411. 52 cubic centimeters

Finding Surface Area l Now we’re going to talk about how to find the surface area of rectangular prisms and cylinders.

Surface Area: Rectangular Prisms l The formula for finding the surface area of a rectangular prism is 2(length x width) + 2(length x height) + 2(width x height).

Surface Area: Rectangular Prisms l l l Suppose you have a rectangular prism that is 7 meters long, 3 meters high, and 4 meters wide. What is the surface area of this rectangular prism? SA = 2(7 x 4) + 2(7 x 3) + 2(4 x 3) SA = 2(28) + 2(21) + 2(12) SA = 56 + 42 + 24 SA = 122 square meters

Surface Area: Cylinders l The formula for finding the surface area of a cylinder is SA = (2 x pi x radius squared) + (2 x pi x radius x height)

Surface Area: Cylinders l Suppose you have a cylinder with a height of 6 feet and a radius of 2 feet. l What is the surface area of this cylinder? l SA = (2 x pi x 2^2) + (2 x pi x 2 x 6) l SA = (2 x 3. 14 x 4) + (2 x 3. 14 x 12) l SA = 25. 12 + 75. 36 l SA = 100. 48 square feet

Remember… l Since multiplication is commutative, it doesn’t matter what order you multiply your numbers in when you find volume.