Transformation of determinant to trigonometric determinant 2 -5 3 1 -2 2 -4 0 1 3 -1 3 4 -1 3 5 0 1 1 -5 3 1 -2 5 -1 -4 2 -3 2 0 5 1

Transformation of determinant to trigonometric determinant 2 -5 3 1 -2 2 -4 0 1 3 -1 3 4 -1 3 5 0 1 1 -5 3 1 -2 5 -1 -4 2 -3 2 0 5 1

Just be patient
First add the second line to the fourth line and kill the 1 in the second line. The second line becomes 0
Add a new second line to the third line and kill the first line in the third line. The third line becomes 0 0
Then multiply the first line by a factor of 1 / 2 and add it to the fourth line to kill - 1
Let's see what the new determinant is. The second and third rows are multiplied by a coefficient to add to the fourth row
Until the fourth line becomes 0
That's it

Let a be a matrix of order 3, and the value of determinant A is 1 / 2. What is the determinant value of (2a) ∧ - 1-5a *?

Because a * = |a ^ - 1 = (1 / 2) a ^ - 1
therefore
|(2A)^-1-5A*|
= |(1/2)A^-1-(5/2)A^-1|
= |(-2)A^-1|
= (-2)^3 |A^-1|
= -8 |A|^-1
= -16.

Let the determinant of matrix A of order 3 be set at 2, and find | - 5A|

|-5A|=-125|A|=-250

The degree of one angle in a triangle is equal to the sum of the degrees of the other two angles. Try to judge the shape of the triangle, and complete the correct answer process

a+b+c=180
a,b,c>0
a=b+c
∴2a=180
a=90
So right triangles

A triangle in which the degree of one angle is equal to the sum of the degrees of the other two angles is a () triangle
A. Acute angle B. right angle C. obtuse angle

The maximum angle of this triangle is: 180 ° 2 = 90 °, the angle of 90 ° is a right angle, and a triangle with a right angle is a right triangle

If one angle of a triangle is equal to the difference between the other two angles, then the triangle is a triangle______ A triangle

Let the three angles of a triangle be a, B and C respectively, then we can get a + B + C = 180 ° a − B = C from the meaning of the question, and a = 90 ° from the solution, so this triangle is a right triangle

The sum of the internal angles of a triangle is 180 degrees. How many degrees is the largest angle greater than or equal to, and how many degrees is the smallest angle less than or equal to?

It's all 60 degrees

In a triangle, the maximum angle is twice the minimum angle, and the maximum angle is 20 ° larger than the other angle

Let the minimum angle degree be x, then the maximum angle is 2x, and the other angle is 2x-20 °. From the equation, x + 2x + 2x-20 ° = 180 ° and the solution, x = 40 °. Answer: the minimum angle degree of this triangle is 40 °

In △ ABC, the degree of the external angle adjacent to ∠ B is___ ．

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