How Do You Determine the Angle of Rotation from a 2x2 Matrix?

In summary, the conversation discusses finding the angle of rotation from a given matrix. It is determined that the angle can be calculated using inverse sin and cos functions. The overall transformation is determined to be either 123.9 or 56.1 degrees, which add up to 180 degrees. The correct form of a rotation matrix is also mentioned.
  • #1
Natasha1
493
9
I just wanted to know how I could work out the angle of rotation from the following matrix -0.6, -0.8 (top) and 0.8, -0.6 (bottom)? :frown:

Is this possible or am I missing something here?
 
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  • #2
Rotation matrices have a certain form (cos, sin, -sin, cos) or something. You can do inverse sin, or cos, so all is well.
 
  • #3
right,

so I get:

a (top left of matrix) => cos-1 (-0.6) = 126.9 degrees

b (top right of matrix) => -sin-1 (-0.8) = 53.1 degrees

c (bottom left of matrix) => sin-1 (0.8) = 53.1 degrees

d (bottom right of matrix) => cos-1 (-0.6) = 126.9 degrees

What is the overall transformation? Is is 126.9 + 53.1 = 180 degrees?
 
  • #4
It can't be 180 degrees, since that would give you a matrix of (-1, 0 , 0, -1), in the order, top left, top right, bottom left and bottom right, i think. I think that the angle of rotation from the positive x-axis is 126.9 degrees, but I'm not entirely sure.
 
  • #5
It's either 123.9 or 56.1 (and of course they add up to 180), check the correct form of a rotation matrix in your notes.
 

Related to How Do You Determine the Angle of Rotation from a 2x2 Matrix?

1. What are matrices and why are they important in science?

Matrices are rectangular arrays of numbers or symbols that are used to represent and manipulate mathematical data in various scientific fields. They are important because they provide a convenient way to organize and analyze complex data sets, and they are also used in many applications, such as computer graphics, cryptography, and quantum mechanics.

2. How are matrices used in transformations?

Matrices are used in transformations to represent the relationship between a set of input values and a corresponding set of output values. These transformations can be used to rotate, scale, translate, or reflect objects in two or three dimensions. By applying matrix operations to these transformations, scientists can accurately model and predict the behavior of physical systems.

3. What is the difference between a matrix and a vector?

A matrix is a rectangular array of numbers, while a vector is a one-dimensional array of numbers. Matrices can have multiple rows and columns, while vectors only have one row or column. Vectors are often used to represent quantities such as position, velocity, or force, while matrices are used to represent transformations or sets of equations.

4. How do matrices relate to linear algebra?

Matrices are a fundamental concept in linear algebra, which is a branch of mathematics that deals with linear equations, vector spaces, and transformations. Linear algebra provides a powerful framework for solving problems in mathematics, physics, engineering, and other scientific fields. Matrices are used extensively in linear algebra to represent and manipulate linear transformations and systems of linear equations.

5. Can matrices be inverted?

Yes, matrices can be inverted as long as they are square and their determinant is non-zero. The inverse of a matrix is a matrix that, when multiplied by the original matrix, yields the identity matrix. Inverting matrices is useful in solving systems of linear equations, calculating the inverse of a transformation, and performing other mathematical operations.

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