Flashcards in Test 1 Deck (20):

1

## Finding an exact angle between two vectors

### cos x = the dot product / the magnitudes multiplied

2

## Finding the area of a triangle made by three vectors

### Combine one vector with each of the other two (i.e. PQ and PR) and find their cross product, then square each component and add them together under a radical and divide by 2

3

## Finding the equation of a sphere with a certain radius

### Like a circle just with the z component

4

## Finding a unit vector in the direction a + b

### Add the vectors together and divide by the magnitude of the two added vectors

5

## Finding projection of a onto b and its magnitude

### a dot b / b dot b all multiplied by b; magnitude if found how it normally is after the projection is found

6

## Explaining the direction and magnitude of the cross product of any two 3d vectors

### The direction is orthagonal to the vectors and the length is the area of the parallelogram created by the two vectors

7

## Finding the parallelepiped created by three vectors

### Do it like a normal cross product but make the top vector the third vector instead of i + j + k

8

## Finding parametric equations of lines through two points

### vector 2 + (vector 2 - vector 1)t then split it up into x=, y=, and z=

9

## Finding the equation of a plane containing three points

### Combine one point with the two others to make two vectors then cross them; use the equation (x-x1) + (y-y1) + (z-z1) = 0 and multiply that with the vector found by crossing the vectors

10

## Finding an expression for the angle between two planes

### cos^-1 (absolute value of the dot product of the two / both of the magnitudes multiplied together)

11

## Writing the parametric equation for the line of intersection of two planes

### Find a point on the line using a system of equations then cross the coefficients of the two planes; write it like (x from point on plane) + (x from crossed vector)t for x, y, and z then transfer to fit with x=, y=, and z=

12

## Find the distance between R and a plane

### Make a vector with the given point and a point on the plane then find the absolute value of the dot product of that point and the point made by the coefficients of the equation of the plane and divide that by the magnitude of the vector made by the coefficients of the equation of the plane

13

## Finding the distance between a point and a line

### Use the vector attached to the t-values of the given line and cross that with the combination of the given point and a point on the given line; use that new vector and cross it with the combination vector; use that magnitude and divide it by the magnitude of the vector

14

## The shape created by the traces of two hyperbolas and an ellipse

### elliptic hyperboloid

15

## The shape created by two parabolas and a hyperbolla

### hyperbolic paraboloid

16

## The shape created by three ellipses

### ellipsoid

17

## The shape made if one variable is infinite

### cylinder

18

## Finding velocity, speed, and acceleration

### Velocity is just the derivative of the vector and speed is its magnitude; acceleration is the derivative of velocity

19

## T, N, B and curvature

###
T= velocity / magnitude of velocity

N= T' / magnitude of T'

B= T x N

Curvature= magnitude of r' x r'' / magnitude of r' cubed

20