The volume of the region in the first octant (x>=0,y>=0,z>=0) bounded ...
Problem:
Find the volume of the region in the first octant (x>=0, y>=0, z>=0) bounded by the cylinder x^2 y^2=4, the plane z=2, and the plane y=4.
Solution:
To find the volume of the given region, we need to determine the limits of integration for each variable and set up the triple integral.
Limit of Integration:
To determine the limits of integration, we need to visualize the region in the first octant.
1. xy-plane (z=0):
- We are given that x>=0 and y>=0, so the region lies in the first quadrant of the xy-plane.
- The equation of the cylinder x^2 y^2=4 represents a hyperbola in the xy-plane.
- The hyperbola opens along the x-axis and y-axis and passes through the points (2, 0) and (-2, 0).
- The region bounded by the cylinder x^2 y^2=4 in the xy-plane is shown below:
![xy-plane](https://edurevnotes.s3.amazonaws.com/image_1626464917.png)
2. xz-plane (y=0):
- Since y>=0, the plane y=0 is the xz-plane.
- The given plane z=2 intersects the xz-plane at z=2.
- The region bounded by the plane z=2 in the xz-plane is shown below:
![xz-plane](https://edurevnotes.s3.amazonaws.com/image_1626465203.png)
3. yz-plane (x=0):
- Since x>=0, the plane x=0 is the yz-plane.
- The plane y=4 intersects the yz-plane at y=4.
- The region bounded by the plane y=4 in the yz-plane is shown below:
![yz-plane](https://edurevnotes.s3.amazonaws.com/image_1626465291.png)
Triple Integral Setup:
We can set up the triple integral by integrating with respect to x, y, and z in the following order:
∫∫∫dV
1. The limits of integration for x are from 0 to x_max.
2. The limits of integration for y are from 0 to y_max(x).
3. The limits of integration for z are from 0 to 2.
Calculating x_max and y_max(x):
To calculate x_max, we need to find the x-coordinate where the hyperbola x^2 y^2=4 intersects the yz-plane (x=0).
Substituting x=0 into the equation, we get y^2=4, which gives y=±2.
Since we are in the first octant (y>=0), x_max=0.
To calculate y_max(x), we need to find the y-coordinate where the hyperbola x^2 y^2=4 intersects the xy-plane (z=0).
Substituting z=0 into the equation, we get x^2 y^2=4, which simplifies to y^2=4/x^2.
The volume of the region in the first octant (x>=0,y>=0,z>=0) bounded ...
Given information:
- Region: First octant (x>=0,y>=0,z>=0)
- Bounded by: Cylinder x^2 y^2=4 and Plane z=2 and z y=4
Step 1: Visualizing the region
To understand the region, let's visualize the equations in a 3D coordinate system.
Step 2: Understanding the equations
- Cylinder equation: x^2 y^2=4 represents a cylinder centered at the origin with a radius of 2 along the x and y axes.
- Plane equation: z=2 represents a horizontal plane located at z=2.
- Plane equation: z y=4 represents a slanted plane that intersects the y-axis at y=4 and passes through the origin.
Step 3: Finding the boundaries of the region
To find the boundaries of the region, we need to determine the points where the cylinder intersects with the planes.
- Cylinder intersection with z=2:
- Substitute z=2 into the cylinder equation: x^2 y^2=4.
- Simplify the equation: x^2 y^2=4 becomes x^2 y^2-4=0.
- Factor the equation: (x y-2)(x y+2)=0.
- Solve for x y=2: x=2, y=1. (Point A)
- Solve for x y=-2: x=-2, y=1. (Point B)
- Cylinder intersection with z y=4:
- Substitute z y=4 into the cylinder equation: x^2 (4/y)^2=4.
- Simplify the equation: x^2 (16/y^2)=4.
- Rearrange the equation: x^2=4y^2/16.
- Simplify further: x^2=y^2/4.
- Take square root: x=y/2 or x=-y/2.
- Substitute x into the plane equation: z y=4.
- For x=y/2: (y/2) y=4, y^2=8.
- Solve for y: y=2√2. (Point C)
- For x=-y/2: (-y/2) y=4, y^2=-8.
- No solution since y cannot be negative.
Step 4: Finding the volume
To find the volume of the region, we need to integrate the function f(x, y, z)=1 over the region.
- The region can be divided into two parts: the triangular region ABC and the rectangular region ABDC.
- The volume of the triangular region ABC can be calculated using the formula for the volume of a pyramid: V_triangular = (1/3) * base_area * height.
- The base_area is given by the area of triangle ABC: (1/2) * base * height = (1/2) * 4 * 2√2 = 4√2.
- The height is the distance between the plane z=2 and the xy-plane, which is 2.
- Substituting the values: V_triangular = (1/3) * 4√2 * 2 =