Calculus 3 : 3-Dimensional Space

Study concepts, example questions & explanations for Calculus 3

varsity tutors app store varsity tutors android store

Example Questions

Example Question #151 : Calculus 3

Find the equation of the plane given by the normal vector \(\displaystyle n=\left \langle 7,5,2\right \rangle\) and a point on the plane \(\displaystyle \left ( 1,3,5\right )\)

Possible Answers:

\(\displaystyle 7x+5y+2z=32\)

\(\displaystyle 9x+4y+2z=32\)

\(\displaystyle 7x+5y+2z=22\)

\(\displaystyle 7x+5y-4z=10\)

Correct answer:

\(\displaystyle 7x+5y+2z=32\)

Explanation:

To find the equation of the plane with a normal vector \(\displaystyle n=\left \langle A,B,C\right \rangle\) and a point \(\displaystyle (x_0,y_0,z_0)\), we use the formula

\(\displaystyle A(x-x_0)+B(y-y_0)+C(z-z_0)=0\)

Using the information from the problem statement, we get 

\(\displaystyle 7(x-1)+5(y-3)+2(z-5)=0\)

This simplifies to \(\displaystyle 7x+5y+2z=32\)

 

Example Question #41 : 3 Dimensional Space

Find the equation of the plane given by the normal vector \(\displaystyle n=\left \langle 2,-5,6\right \rangle\) and a point on the plane \(\displaystyle \left ( 3,7,9\right )\)

Possible Answers:

\(\displaystyle 2x-5y+6z=25\)

\(\displaystyle 2x+5y+6z=25\)

\(\displaystyle 2x-5y+6z=16\)

\(\displaystyle 2x-5y+6z=24\)

Correct answer:

\(\displaystyle 2x-5y+6z=25\)

Explanation:

To find the equation of the plane with a normal vector \(\displaystyle n=\left \langle A,B,C\right \rangle\) and a point \(\displaystyle (x_0,y_0,z_0)\), we use the formula

\(\displaystyle A(x-x_0)+B(y-y_0)+C(z-z_0)=0\)

Using the information from the problem statement, we get 

\(\displaystyle 2(x-3)-5(y-7)+6(z-9)=0\)

This simplifies to \(\displaystyle 2x-5y+6z=25\)

 

Example Question #42 : 3 Dimensional Space

Find the equation of the plane that contains the point \(\displaystyle \left ( 3,-6,7\right )\) and has a normal vector \(\displaystyle n=\left \langle 4,2,1\right \rangle\)

Possible Answers:

\(\displaystyle 3x+2y+z=7\)

\(\displaystyle 4x+2y-z=7\)

\(\displaystyle 4x+2y+z=7\)

\(\displaystyle 4x+2y+z=14\)

Correct answer:

\(\displaystyle 4x+2y+z=7\)

Explanation:

To find the equation of a plane with a point \(\displaystyle (x_0,y_0,z_0)\) and a normal vector \(\displaystyle n=\left \langle A,B,C\right \rangle\), we use the formula

\(\displaystyle A(x-x_0)+B(y-y_0)+C(z-z_0)=0\)

Using the information from the problem statement, we get

\(\displaystyle 4(x-3)+2(y+6)+1(z-7)=0\)

Simplifying, we then get

\(\displaystyle 4x+2y+z=7\)

Example Question #151 : Calculus 3

Find the equation of the plane that contains the point \(\displaystyle (5,-1,2)\) and contains the normal vector \(\displaystyle \left \langle 4,5,5\right \rangle\)

Possible Answers:

\(\displaystyle 4x+5y+5z=20\)

\(\displaystyle 4x+y+3z=25\)

\(\displaystyle 2x+5y+5z=25\)

\(\displaystyle 4x+5y+5z=25\)

Correct answer:

\(\displaystyle 4x+5y+5z=25\)

Explanation:

To find the equation of a plane with a point \(\displaystyle (x_0,y_0,z_0)\) and a normal vector \(\displaystyle n=\left \langle A,B,C\right \rangle\), we use the formula

\(\displaystyle A(x-x_0)+B(y-y_0)+C(z-z_0)=0\)

Using the information from the problem statement, we get

\(\displaystyle 4(x-5)+5(y+1)+5(z-2)=0\)

Simplifying, we then get

\(\displaystyle 4x+5y+5z=25\)

Example Question #45 : 3 Dimensional Space

Find the equation of the plane containing these points:

\(\displaystyle A=(1, 2, 3)\)\(\displaystyle B=(0, 3, -6)\)\(\displaystyle C=(-2, 4, 2)\)

Possible Answers:

\(\displaystyle x+10y+z=-24\)

\(\displaystyle x+2y+3z=24\)

\(\displaystyle x+10y+z=0\)

\(\displaystyle x+10y+z=24\)

Correct answer:

\(\displaystyle x+10y+z=24\)

Explanation:

To find the equation of a plane, we need the normal vector and a point on the plane. The normal vector is found by taking the cross product of two vectors on the plane.

To find two vectors, simply find the difference between terminal and initial points:

\(\displaystyle \vec{AB}=\left \langle -1, 1, -9\right \rangle\)\(\displaystyle \vec{BC}=\left \langle -2, 1, -8 \right \rangle\)

Now, we can write the determinant in order to take the cross product of the two vectors:

\(\displaystyle \begin{vmatrix} \hat{i}& \hat{j}&\hat{k} \\ -1&1 &-9 \\ -2&1 &-8 \end{vmatrix}\)

where i, j, and k are the unit vectors corresponding to the x, y, and z direction respectively.

Next, we take the cross product. One can do this by multiplying across from the top left to the lower right, and continuing downward, and then subtracting the terms multiplied from top right to the bottom left:

\(\displaystyle -8\hat{i}-\hat{k}+18\hat{j}-(-2\hat{k}-9\hat{i}+8\hat{j})=\hat{i}+10\hat{j}+\hat{k}=\left \langle 1, 10, 1\right \rangle\)

Plugging this into the formula

\(\displaystyle a(x-x_0)+b(y-y_0)+c(z-z_0)=0\), where \(\displaystyle \vec{n}=\left \langle a, b, c\right \rangle\) and \(\displaystyle (x_0, y_0, z_0)\) is any of the given points (for example \(\displaystyle (1, 2 ,3)\)), we get

\(\displaystyle 1(x-1)+10(y-2)+1(z-3)=0\)

which simplified becomes

\(\displaystyle x+10y+z=24\)

Example Question #43 : Equations Of Lines And Planes

Find the equation of the plane that contains the point \(\displaystyle \left ( 3,0,1\right )\) and has a normal vector \(\displaystyle n=\left \langle 4,4,1\right \rangle\)

Possible Answers:

\(\displaystyle 4x+3y+z=13\)

\(\displaystyle 4x+4y+z=13\)

\(\displaystyle 4x+4y+z=10\)

\(\displaystyle 4x+4y-z=13\)

Correct answer:

\(\displaystyle 4x+4y+z=13\)

Explanation:

To find the equation of a plane with a point \(\displaystyle (x_0,y_0,z_0)\) and normal vector \(\displaystyle n=\left \langle A,B,C\right \rangle\), we use the following equation:

\(\displaystyle A(x-x_0)+B(y-y_0)+C(z-z_0)=0\)

Plugging in the information from the problem statement, we get

\(\displaystyle 4(x-3)+4(y-0)+1(z-1)=0\)

Isolating the variables to one side gets us

\(\displaystyle 4x+4y+z=13\)

Example Question #43 : 3 Dimensional Space

Find the equation of the plane that contains the point \(\displaystyle \left ( 2,1,5\right )\) and has a normal vector \(\displaystyle n=\left \langle 2,5,2\right \rangle\)

Possible Answers:

\(\displaystyle 2x+5y+2z=14\)

\(\displaystyle 2x+5y+2z=19\)

\(\displaystyle 2x-5y+2z=19\)

`\(\displaystyle 2x+6y+2z=19\)

Correct answer:

\(\displaystyle 2x+5y+2z=19\)

Explanation:

To find the equation of a plane with a point \(\displaystyle (x_0,y_0,z_0)\) and normal vector \(\displaystyle n=\left \langle A,B,C\right \rangle\), we use the following equation:

\(\displaystyle A(x-x_0)+B(y-y_0)+C(z-z_0)=0\)

Plugging in the information from the problem statement, we get

\(\displaystyle 2(x-2)+5(y-1)+2(z-5)=0\)

Isolating the variables to one side gets us

\(\displaystyle 2x+5y+2z=19\)

Example Question #44 : 3 Dimensional Space

Find the equation of the plane that contains the point \(\displaystyle (3,-6,7)\) and a normal vector \(\displaystyle n=\left \langle 1,2,1\right \rangle\)

Possible Answers:

\(\displaystyle 2x+2y+z=-2\)

\(\displaystyle x-2y-4z=-4\)

\(\displaystyle x+2y+z=-2\)

\(\displaystyle x+2y-z=-2\)

Correct answer:

\(\displaystyle x+2y+z=-2\)

Explanation:

To find the equation of the plane containing a point \(\displaystyle (x_0,y_0,z_0)\) and a normal vector \(\displaystyle n=\left \langle A,B,C\right \rangle\), we use the formula:

\(\displaystyle A(x-x_0)+B(y-y_0)+C(z-z_0)=0\)

Plugging in the known values and solving, we get

\(\displaystyle 1(x-3)+2(y+6)+1(z-7)=0\)

Simplifying, we get

\(\displaystyle x+2y+z=-2\)

 

Example Question #41 : 3 Dimensional Space

Find the equation of the plane that contains the point \(\displaystyle (5,4,1)\) and a normal vector \(\displaystyle n=\left \langle 3,1,5\right \rangle\)

Possible Answers:

\(\displaystyle 3x-y+5z=24\)

\(\displaystyle 5x+y+5z=22\)

\(\displaystyle 3x+y+5z=24\)

\(\displaystyle 3x+4y+5z=24\)

Correct answer:

\(\displaystyle 3x+y+5z=24\)

Explanation:

To find the equation of the plane containing a point \(\displaystyle (x_0,y_0,z_0)\) and a normal vector \(\displaystyle n=\left \langle A,B,C\right \rangle\), we use the formula:

\(\displaystyle A(x-x_0)+B(y-y_0)+C(z-z_0)=0\)

Plugging in the known values and solving, we get

\(\displaystyle 3(x-5)+1(y-4)+5(z-1)=0\)

Simplifying, we get

\(\displaystyle 3x+y+5z=24\)

 

Example Question #42 : 3 Dimensional Space

Find the equation of the plane given by a point on the plane \(\displaystyle (3,-4,3)\) and the normal vector \(\displaystyle n=\left \langle 8,4,-5\right \rangle\)

Possible Answers:

\(\displaystyle 6x+4y-5z=-7\)

\(\displaystyle 8x+2y-5z=-7\)

\(\displaystyle 8x+4y-5z=-7\)

\(\displaystyle 8x+4y-3z=-7\)

Correct answer:

\(\displaystyle 8x+4y-5z=-7\)

Explanation:

To find the equation of a plane given a point on the plane \(\displaystyle (x_0,y_0,z_0)\) and a normal vector to the plane \(\displaystyle n=\left \langle A,B,C\right \rangle\), we use the following equation

\(\displaystyle A(x-x_0)+B(y-y_0)+C(z-z_0)=0\)

Plugging in the information from the problem statement, we get

\(\displaystyle 8(x-3)+4(y+4)-5(z-3)=0\)

Rearranging, we get

\(\displaystyle 8x+4y-5z=-7\)

Learning Tools by Varsity Tutors