### All Advanced Geometry Resources

## Example Questions

### Example Question #5 : Surface Area

**Possible Answers:**

**Correct answer:**

The formula for the surface area of a cone is:

,

where represents the radius of the cone base and represents the slant height of the cone.

Plugging in our values, we get:

### Example Question #5 : Surface Area

The surface area of cone is . If the radius of the base of the cone is , what is the height of the cone?

**Possible Answers:**

**Correct answer:**

To figure out , we must use the equation for the surface area of a cone, , where is the radius of the base of the cone and is the length of the diagonal from the tip of the cone to any point on the base's circumference. We therefore first need to solve for by plugging what we know into the equation:

This equation can be reduced to:

For a normal right angle cone, represents the line from the tip of the cone running along the outside of the cone to a point on the base's circumference. This line represents the hypotenuse of the right triangle formed by the radius and height of the cone. We can therefore solve for using the Pythagorean theorem:

so

Our is therefore:

The height of cone is therefore

### Example Question #1 : How To Find The Surface Area Of A Cone

A circle of radius five is cut into two pieces, and . The larger section is thrown away. The smaller section is curled until the two straight edges meet, and a bottom is made for the cone.

What is the area of the bottom?

**Possible Answers:**

**Correct answer:**

When the smaller portion of the circle is curled in, it will make the top of a cone. The circumfrence of the circle on the bottom is (where r is the radius of the circle on the bottom). The circumference of the bottom is also of the circumfrence of the original larger circle, which is (where R is the radius of the original, larger circle)

Therefore we use the circumference formula to solve for our new r:

Substituting this value into the area formula, the area of the small circle becomes:

### Example Question #2 : How To Find The Surface Area Of A Cone

A cone has a bottom area of and a height of , what is the surface area of the cone?

**Possible Answers:**

**Correct answer:**

The area of the bottom of the cone yields the radius,

The height of the cone is , so the Pythagorean Theorem will give the slant height,

The area of the side of the cone is and adding that to the given as the area of the circle, the surface area comes to

### Example Question #3 : Advanced Geometry

If the surface area of a right angle cone is , and the distance from the tip of the cone to a point on the edge of the cone's base is , what is the cone's radius?

**Possible Answers:**

**Correct answer:**

Solving this problem is going to take knowledge of Algebra, Geometry, and the equation for the surface area of a cone: , where is the radius of the cone's base and is the distance from the tip of the cone to a point along the edge of the cone's base. First, let's substitute what we know in this equation:

We can divide out from every term in the equation to obtain:

We see this equation has taken the form of a quadratic expression, so to solve for we need to find the zeroes by factoring. We therefore need to find factors of that when added equal . In this case, and :

This gives us solutions of and . Since represents the radius of the cone and the radius must be positive, we know that is our only possible answer, and therefore the radius of the cone is .

### Example Question #3 : Advanced Geometry

For a right circular cone , the radius is and the height of the cone is . What is the surface area of the cone in terms of ?

**Possible Answers:**

**Correct answer:**

To solve this problem, we will need to use the formula for finding the surface area of a cone, , where is the length of the diagonal from the circle edge of the cone to the top. Since we are not given s, we must find it by using Pythagorean's Theorem:

.

is a prime number, so we cannot factor the radical any further. Therefore, our equation for our surface area of becomes:

, which is our final answer.

### Example Question #35 : 3 Dimensional Geometry

If the surface area of cone is , and the distance between the cone's tip and a point on the cone's circular base is , what is the radius of the cone?

**Possible Answers:**

**Correct answer:**

To find out the radius, we must use our knowledge of the formula for the surface area of a cone: , where is the radius of the cone and is the distance from the tip of the cone to any point along the circumference of the cone's base. We can plug in what we already know into the above equation:

We can divide out from each term to obtain:

We now can recognize that the above is a quadratic expression, so to solve for we can find the zeroes of the equation by factoring. We need two numbers which will multiply to but will add to (in this case and ). Therefore, we can factor the above to the following:

.

Our two solutions are therefore and . Since represents the radius of the base of the cone, it must be positive, and that leaves as our one and only answer.

### Example Question #36 : 3 Dimensional Geometry

Find the surface area of a cone with a base diameter of and a slant height of .

**Possible Answers:**

**Correct answer:**

The Surface Area of a cone is:

Given the base diameter is 6, the radius will be 3. The given slant height is 10.

Substitute the radius and slant height into the equation to find surface area.

### Example Question #37 : 3 Dimensional Geometry

Find the surface area of a cone with a base area of and a slant height of .

**Possible Answers:**

**Correct answer:**

The surface area of a cone is:

Given the base area is , the base of the cone resembles a circle. Using the base area, it is necessary to find the radius.

Since radius of the base is 2, and slant height is 6, substitute these into the surface area equation.

### Example Question #1 : Solid Geometry

Find the surface area of a cone with a base diameter of and a height of .

**Possible Answers:**

**Correct answer:**

The Surface Area of a cone is:

Given the base diameter is 6, the radius of the base is 3. The height is 10. We will substitute these values to find the slant height by using the Pythagorean Theorem.

Substitute slant height and radius into the Surface Area equation.