Finding domains of 3d quadratic surfaces

In summary, the conversation discusses using inequalities to determine if a point is internal or external to a shape. It is suggested to use a test point and check if its coordinates satisfy the inequalities. The speaker also mentions that for a cone, not all points satisfy the inequality and asks about finding the external points of the cone.
  • #1
DottZakapa
239
17
Homework Statement
##z^2\leq x^2+y^2, z\geq x^2+y^2##
Relevant Equations
domain
##z^2\leq x^2+y^2, z\geq x^2+y^2##
I know the shapes of those inequalities, but the question is:
How do i find if the point are external the shape or internal?
 
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  • #2
Take a simple test point and see if its coordinates satisfy the inequalities.
 
  • #3
Math_QED said:
Take a simple test point and see if its coordinates satisfy the inequalities.
in the case of the cone any number satisfy the inequality, but what if i want the external points of the cone
 
  • #4
DottZakapa said:
in the case of the cone any number satisfy the inequality, but what if i want the external points of the cone
That's not true about the cone. For example, the point (1, 1, 2) is outside the cone.
 

1. What is a 3d quadratic surface?

A 3d quadratic surface is a three-dimensional shape that can be represented by a quadratic equation, where the highest power of the variables is two. It is a type of geometric surface that can be described as a curved or rounded shape.

2. How do you find the domain of a 3d quadratic surface?

The domain of a 3d quadratic surface refers to the set of all possible input values that can be plugged into the equation to produce a valid output. To find the domain, you can analyze the equation and determine any restrictions on the variables, such as square roots or fractions. These restrictions will give you the range of values that are allowed in the domain.

3. Can a 3d quadratic surface have an infinite domain?

Yes, a 3d quadratic surface can have an infinite domain. This can occur when there are no restrictions on the variables in the equation, or when the equation contains variables with an infinite range, such as x or y. In these cases, the surface will extend infinitely in all directions.

4. How do you graph a 3d quadratic surface?

To graph a 3d quadratic surface, you can use a three-dimensional coordinate system and plot points that satisfy the equation. You can also use software or online tools to create a 3d graph of the surface. It is important to remember that a 3d quadratic surface is not a flat shape, so it may be difficult to visualize on a two-dimensional surface.

5. What are some real-world applications of 3d quadratic surfaces?

3d quadratic surfaces have many real-world applications in fields such as engineering, physics, and computer graphics. They can be used to model the shape of objects, such as buildings or bridges, and to analyze their structural stability. In physics, 3d quadratic surfaces are used to represent the path of projectiles or the shape of gravitational fields. In computer graphics, they are used to create realistic 3d models of objects and environments.

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