The calculation of determinant is changed into upper triangle or lower triangle Please don't say the nature, I know the nature What I want to know is what skills are there? For example, if I have a determinant in my hand, where should I start? In other words, for this determinant, what is the solution? (it can be illustrated by examples. If there are satisfactory ones, add them to 500)

The calculation of determinant is changed into upper triangle or lower triangle Please don't say the nature, I know the nature What I want to know is what skills are there? For example, if I have a determinant in my hand, where should I start? In other words, for this determinant, what is the solution? (it can be illustrated by examples. If there are satisfactory ones, add them to 500)

A determinant of the lower triangle is often used, first determine the element (1,1) position (generally use the simplest), and then the elements below the first column are all changed to 0, and then determine the element (2,2) position, and then the elements below the element (2,2) in the second column are all changed to 0, in this way, can be transformed into a triangular determinant

What is the upper triangle, lower triangle determinant? Linear algebra master into!
I'm preview, so many things are not very clear,
The problem with the title is not in the book about trigonometric determinants
Why do I have to simplify the determinant into upper triangle or lower triangle determinant? Is it because it can be calculated directly or it is very convenient to calculate? The examples in my book are all directly transformed into upper triangle determinant, and then I get the answer. How does it calculate?

Linear algebra is a little difficult at the beginning, because there are some new concepts and symbols. It's easy to understand, because it's not profound. For your problem, the elements that the diagonal line of determinant from the upper left corner to the lower right corner passes through are called main diagonal elements. If all the elements below the main diagonal are 0, and not all the elements above the main diagonal are 0, then

Is there any difference between the upper trigonometric determinant and the lower trigonometric determinant
Is it just the difference between the top of one main diagonal and the bottom of the other?

1. From (4 × 4), the determinant can only be expanded by row or column, and the workload increases rapidly according to the N & sup2; relation
If it can be transformed into up triangular determinant or down triangular determinant
The value of determinant is equal to the product of diagonal
This is the original intention of trigonometric determinant
2. The structure of the multiple linear equations corresponding to the upper triangle and the lower triangle is as follows
Upper triangle (take six elements as an example): [all elements below diagonal are 0]
x+y+z+u+v+w = a
y+z+u+v+w = b
z+u+v+w = c
u+v+w = d
v+w = e
w = d
Lower triangle (take six elements as an example): [all elements above diagonal are 0]
x = a
x+y = b
x+y+z = c
x+y+z+u = d
x+y+z+u+v = e
x+y+z+u+v+w = f
Therefore, there is no difference between the upper and the lower, and the value used to calculate the determinant is the same
The structure of the corresponding multivariate linear equations is the resolution form and the extension form
If you don't understand, you are welcome to discuss

To know the length of the three sides of the triangle, find the degree of the three angles of the triangle
We need a formula
Everybody answer quickly

The square of cosa = (the square of B + the square of C - the square of a) and then divided by 2BC. The other two angles are the same, that is, the cosine theorem. Typing on mobile phones is troublesome

In a triangle, angle 1 is three times the degree of angle 2, and angle 2 is two times the degree of angle 3. So what is the largest angle in the triangle?

If the degree of angle 3 is a, then angle 2 is 2a and angle 1 is 6A
A+2A+6A=180
A = 20 degrees
Angle 1 = 20 * 6 = 120 degrees

In any triangle, how many degrees is the largest angle at least?

In any triangle, the degree of the largest angle is at least 60 degrees, and the maximum is less than 180 degrees

The acute degree of a right triangle is 45 degrees. What is the area of the right triangle

Right angle side × right angle side △ 2

There is a right triangle with an angle of 30 degrees and the length of one side is 1cm

Dear teachers, dear students: Hello everyone! It's a new semester and a new beginning. Everything will start again. This semester, the discipline commissar is the class cadre I want to run for. I love the collective and unite my classmates. But I also have many shortcomings. In the class, I'm not the best, but I believe that in the future

Is the sum of the degrees of the angles of all triangles equal to 180 degrees

Yes

It is known that the sum of the three internal angles of a triangle is 180 degrees. If the degrees of the three internal angles of a triangle are all prime numbers less than 120, then the degrees of the three internal angles of the triangle are 180 degrees______ ．

Because the sum of three angles is 180 ° and is an even number, one prime number must be 2 ° and the sum of the remaining two prime numbers is 180 ° - 2 ° = 178 ° as long as the sum of the two prime numbers is 178 °, so the end of the two prime numbers is 7 and 1, and less than 120 ° so it may be 61 + 117 or 71 + 107 or 81 + 97 or 91 + 8