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(pi
= Surface
Area Formulas Cube | Rectangular
Prism | Prism | Sphere
| Cylinder | Units Note: "ab" means "a" multiplied by "b". "a2" means "a squared", which is the same as "a" times "a".Be careful!! Units count. Use the same units for all measurements. Examples
In words, the surface area of a cube is the area of the six squares that cover it. The area of one of them is a*a, or a 2 . Since these are all the same, you can multiply one of them by six, so the surface area of a cube is 6 times one of the sides squared.
In words, the surface area of a rectangular prism is the area of the six rectangles that cover it. But we don't have to figure out all six because we know that the top and bottom are the same, the front and back are the same, and the left and right sides are the same. The area of the top and bottom (side lengths a and
c) = a*c. Since there are two of them, you get 2ac. The front and back
have side lengths of b and c. The area of one of them is b*c, and there
are two of them, so the surface area of those two is 2bc. The left and
right side have side lengths of a and b, so the surface area of one of
them is a*b. Again, there are two of them, so their combined surface area
is 2ab.
Surface Area = Lateral area + Area of two ends (Lateral area) = (perimeter of shape b) * L Surface Area = (perimeter of shape b) * L+ 2*(Area of shape b)
Surface Area = Areas of top and bottom +Area of the side Surface Area = 2(Area of top) + (perimeter of top)* height Surface Area = 2(pi r 2) + (2 pi r)* h In words, the easiest way is to think of a can. The surface area is the areas of all the parts needed to cover the can. That's the top, the bottom, and the paper label that wraps around the middle. You can find the area of the top (or the bottom). That's the formula for area of a circle (pi r2). Since there is both a top and a bottom, that gets multiplied by two. The side is like the label of the can. If you peel it off and lay it flat it will be a rectangle. The area of a rectangle is the product of the two sides. One side is the height of the can, the other side is the perimeter of the circle, since the label wraps once around the can. So the area of the rectangle is (2 pi r)* h. Add those two parts together and you have the formula for the surface area of a cylinder. Surface Area = 2(pi r 2) + (2 pi r)* h
These equations will give you correct answers if you keep the units straight. For example - to find the surface area of a cube with sides of 5 inches, the equation is: Surface Area = 6*(5 inches)2 = 6*(25 square inches) = 150 sq. inches |
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= 3.141592...) 
(a is the length of the side of
each edge of the cube)
(a, b, and c are the
lengths of the 3 sides)
(b is the shape
of the ends)
(r is radius of circle)
(h is the height of
the cylinder, r is the radius of the top)
