All Advanced Geometry Resources
Example Questions
Example Question #31 : Solid Geometry
In the figure below, a cone is placed on top of a cylinder so that they share the same base. Find the surface area of the figure.
First, find the lateral surface area of the cone.
Plug in the given slant height and radius.
Next, find the surface area of the cylinder:
The surface area of the cylinder is the sum of the lateral surface area of the cylinder and its two bases. However, since one base of the cylinder is covered up by the cone, we will need to subtract that area out of the total surface area of the cylinder.
Plug in the given height and radius to find the surface area of the cylindrical portion of the figure:
To find the surface area of the figure, add together the lateral area of the cone with the surface area of the cylindrical portion of the figure.
Make sure to round to places after the decimal.
Example Question #32 : Solid Geometry
In the figure below, a cone is placed on top of a cylinder so that they share the same base. Find the surface area of the figure.
First, find the lateral surface area of the cone.
Plug in the given slant height and radius.
Next, find the surface area of the cylinder:
The surface area of the cylinder is the sum of the lateral surface area of the cylinder and its two bases. However, since one base of the cylinder is covered up by the cone, we will need to subtract that area out of the total surface area of the cylinder.
Plug in the given height and radius to find the surface area of the cylindrical portion of the figure:
To find the surface area of the figure, add together the lateral area of the cone with the surface area of the cylindrical portion of the figure.
Make sure to round to places after the decimal.
Example Question #33 : Solid Geometry
In the figure below, a cone is placed on top of a cylinder so that they share the same base. Find the surface area of the figure.
First, find the lateral surface area of the cone.
Plug in the given slant height and radius.
Next, find the surface area of the cylinder:
The surface area of the cylinder is the sum of the lateral surface area of the cylinder and its two bases. However, since one base of the cylinder is covered up by the cone, we will need to subtract that area out of the total surface area of the cylinder.
Plug in the given height and radius to find the surface area of the cylindrical portion of the figure:
To find the surface area of the figure, add together the lateral area of the cone with the surface area of the cylindrical portion of the figure.
Make sure to round to places after the decimal.
Example Question #31 : Solid Geometry
In the figure below, a cone is placed on top of a cylinder so that they share the same base. Find the surface area of the figure.
First, find the lateral surface area of the cone.
Plug in the given slant height and radius.
Next, find the surface area of the cylinder:
The surface area of the cylinder is the sum of the lateral surface area of the cylinder and its two bases. However, since one base of the cylinder is covered up by the cone, we will need to subtract that area out of the total surface area of the cylinder.
Plug in the given height and radius to find the surface area of the cylindrical portion of the figure:
To find the surface area of the figure, add together the lateral area of the cone with the surface area of the cylindrical portion of the figure.
Make sure to round to places after the decimal.
Example Question #31 : How To Find The Surface Area Of A Cone
Figure NOT drawn to scale.
The base of the above cone has circumference 50. Give the surface area of the cone.
Round to the nearest whole number.
The surface area of a cone can be calculated using the formula
where is the radius of the base and is the slant height. The slant height is known to be 20.
The radius of the circular base can be found by dividing its circumference 50 by :
Set and , and evaluate:
Example Question #36 : Solid Geometry
Figure NOT drawn to scale.
The base of the above cone has area 50. Give the surface area of the cone.
Round to the nearest whole number.
The area and the radius of the circular base are related by the formula
The area of the circle is 50, so set , then solve for :
Divide by :
Take the square root of both sides:
The surface area of the cone is the sum of the areas of the base and the lateral area. The lateral area of the cone can be found from the radius and the slant height using the formula
Set and :
Add the area of the base, 50:
Example Question #37 : Solid Geometry
Figure NOT drawn to scale.
The base of the above cone has area 50. Give the surface area of the cone.
Round to the nearest whole number.
The area and the radius of the circular base are related by the formula
The area of the circle is 50, so set , then solve for :
Divide by :
Take the square root of both sides:
Now examine the figure below.
The slant height can be calculated from the height and the radius by way of the Pythagorean Theorem:
The surface area of the cone is the sum of the areas of the base and the lateral area. The lateral area of the cone can be found from the radius and the slant height using the formula
Set and :
Add the area of the base, 50, to this lateral area to obtain the surface area:
.
Example Question #38 : Solid Geometry
Figure NOT drawn to scale.
The base of the above cone has circumference 50. Give the surface area of the cone.
Round to the nearest whole number.
The surface area of a cone can be calculated using the formula
where is the radius of the base and is the slant height.
The radius of the circular base can be found by dividing its circumference 50 by :
Examine the figure below.
The slant height can be calculated from the height and the radius by way of the Pythagorean Theorem:
Set and in the surface area formula:
Example Question #1 : How To Find The Length Of An Edge
What is the length of one edge of a regular tetrahedron whose volume equals ?
None of the above.
The formula for the volume of a tetrahedron is:
.
When we have .
Multiplying the left side by gives us,
, or .
Finally taking the third root of both sides yields
Example Question #1 : Tetrahedrons
A regular tetrahedron has a total surface area of . What is the combined length of all of its edges?
None of the above.
A regular tetrahedron has four faces of equal area made of equilateral triangles.
Therefore, we know that one face will be equal to:
, or
Since the surface of one face is an equilateral triangle, and we know that,
, the problem can be expressed as:
In an equilateral triangle, the height , is equal to so we can substitute for like so:
Solving for gives us the length of one edge.
However, we know that the edge of the tetrahedron is a positive number so .
Since the base is the same as one edge of the tetrahedron, and a tetrahedron has six edges we multiply to arrive at
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