All Intermediate Geometry Resources
Example Questions
Example Question #71 : Cubes
A sphere with a radius of is cut out of a cube that has a side length of . What is the volume of the resulting figure?
Since the cube is bigger, we will be subtracting the volume of the sphere from the volume of the cube.
Start by recalling how to find the volume of a sphere.
Plug in the given radius to find the volume.
Next, recall how to find the volume of a cube:
Plug in the given side length to find the volume of the cube.
Finally, subtract the volume of the sphere from the volume of the cube.
Make sure to round to places after the decimal.
Example Question #72 : Cubes
The above figure shows a triangular pyramid inscribed inside a cube. The pyramid has volume 100. Give the volume of the cube.
Let be the length of one side of the cube. Then the base of the pyramid is a right triangle with legs of length . The area of a right triangle is half the product of the lengths of the legs, so the base has area
The volume of a pyramid is one third the product of its height and the area of its base. The height of the pyramid is , so the volume is
The volume of the cube is , so
,
or, equivalently,
That is, the volume of the cube is six times that of the pyramid, and, since the pyramid has volume 100, the volume of the cube is .
Example Question #1 : How To Find The Surface Area Of A Cylinder
A cylinder has a volume of 16 and a radius of 4. What is its height?
Since the radius is 4, the area of the base is . To cancel out the , the height must be .
Example Question #2 : How To Find The Surface Area Of A Cylinder
What is the surface area of a cylinder with diameter 4 and height 6? The equation to calculate the surface area of a cylinder is:
If the diameter of the cylinder is 4, the radius is equal to 2. Therefore:
Example Question #71 : Solid Geometry
Find the surface area of the following right cylinder:
The answer is . To find the surface area we need to find the area of the top, bottom, and the round side respectively. To find the areas of the top and bottom circles, you would need to use the formula .
Plug in 4 for , and you get , then multiply by 2 for 2 circles to get
Then to get the area of the round side, you would take the circumference times the height. Thus with the formula
you would get
To get your final answer, add and to get
Also you could remember the formula
and plug in and .
Example Question #1 : How To Find The Surface Area Of A Cylinder
Given a cylinder with radius of 5cm and a height of 10cm, what is the surface area of the entire cylinder?
The surface area of the whole cylinder = (2 * area of circle) + lateral area
Think of the lateral area as the paper label on a can; It wraps around the outside of the can while leaving the top and bottom untouched. The area of the circle, times 2, is to account for the top and the bottom of the cylinder.
Area of a circle =
So the area of the circle = , and since there are two circles we have
Now for the lateral area. Notice how if we have a can with a paper label, we can take the label, cut it, and unroll it from the can. In this way, our label now looks like a rectangle with a
height = height and the
width = circumference of the circle.
Circumference =
So our rectangle is going to have a height of 10 and a width of 10. So the lateral area =
So the total surface area =
Example Question #4 : Cylinders
The circumference of the base of a cylinder is and the height of the cylinder is . What is this cylinder's surface area? Round to the tenths place.
The formula to find the surface area of a cylinder is , where is the height of the cylinder and is the radius.
In this kind of equation-based problem, it's helpful to ask "What information do I have?" and "What information is missing that I need?"
The problem provides information for the component of the equation, but not for the component. Instead, we're given information about the circumference of the circular base of the cylinder. The question that arises now is how the radius can be calculated from the circumference. The formula for circumference is: , where is diameter. Radius can be calculated by taking half of the diameter. This means that radius and circumference are related in terms of .
Therefore, the first step for this problem is to solve for .
Because the diameter is , that means that the radius must be .
Now the surface area can be solved for after the and values are substituted into the equation.
Example Question #6 : How To Find The Surface Area Of A Cylinder
Find the surface area of the cylinder below.
To find the surface area of the cylinder, first find the areas of the bases:
Next, find the lateral surface area, which is a rectangle:
Add the two together to get the equation to find the surface area of a cylinder:
Plug in the given height and radius to find the surface area.
Make sure to round to places after the decimal point.
Example Question #7 : How To Find The Surface Area Of A Cylinder
Find the surface area of the given cylinder.
To find the surface area of the cylinder, first find the areas of the bases:
Next, find the lateral surface area, which is a rectangle:
Add the two together to get the equation to find the surface area of a cylinder:
Plug in the given height and radius to find the surface area.
Make sure to round to places after the decimal point.
Example Question #8 : How To Find The Surface Area Of A Cylinder
Find the surface area of the given cylinder.
To find the surface area of the cylinder, first find the areas of the bases:
Next, find the lateral surface area, which is a rectangle:
Add the two together to get the equation to find the surface area of a cylinder:
Plug in the given height and radius to find the surface area.
Make sure to round to places after the decimal point.