Why is the simplest operation of second-order determinant diagonal rule? What is the physical meaning of determinant? What is the physical meaning of determinant? Why do you use diagonal rule to calculate? Some of the questions on the first floor were not answered. I also know the specific calculation method, but I don't understand why the diagonal rule is used, Not the diagonal rule. That is to say, why should determinant be calculated like this?

Why is the simplest operation of second-order determinant diagonal rule? What is the physical meaning of determinant? What is the physical meaning of determinant? Why do you use diagonal rule to calculate? Some of the questions on the first floor were not answered. I also know the specific calculation method, but I don't understand why the diagonal rule is used, Not the diagonal rule. That is to say, why should determinant be calculated like this?

The real algorithm is calculated by row and column factors and co row and column, but in the 2 * 2 row and column, it is exactly equal to ad BC, so there is an intuitive diagonal rule. The physical meaning depends on the specific row and column, and the feeling of determinant is the absolute value of the row and column. And the row and column can be regarded as the operator in vector operation (just like algebra

Solving the determinant of linear algebra
1 2 2 … two
2 2 2 … two
2 2 3 … two
……………
2 2 2 … n
It's better to have ideas and steps

Subtract the first, third, fourth, and N rows from the second row, and then divide them into blocks. The second order in the upper left corner is a block, and the N-2 order in the lower right corner is a block. Therefore, the original formula is equal to the product of the second order determinant in the upper left corner and the N-2 order determinant in the lower right corner. The answer is - 2 * (n-2)!

As shown in the figure, in △ ABC, BD ⊥ AC is in D, CE ⊥ AB is in E, a = 80 ° and the degree of ⊥ BOC is calculated
emergency

Angle EOD = 360-90-90-80 = 100
Angle EOD = angle BOC = 100

As shown in the figure, in △ ABC, BD ⊥ AC, CE ⊥ AB and the vertical feet are D.E., BD and CE respectively. Compared with point O, if ⊥ a = 50 °, calculate the degree of ⊥ BOC
Explore the relationship between BOC and a
(1) Find the degree of ∠ BOC
(2) Explore the relationship between BOC and a

The answer is in progress
∠EOD=∠BOC
∠A+∠AEO+∠EOD+∠ODA=360°
∵∠AEO=∠EDO=90°
∴∠A+∠EOD=180°
∴∠A+∠BOC=180°

As shown in the figure, BD and CE are the heights of △ BAC. The intersection of the two heights and the point o. ∠ BOC = 130 ° is used to calculate the degree of ∠ a

∠ EOD = ∠ BOC = 130 ° (equal to vertex angle)
∠A=360°-90°-90°-130°=50°

It is known that, as shown in the figure △ ABC, the three heights ad, be and CF intersect at point O. if ∠ BAC = 60 °, the degree of ∠ BOC is calculated

In △ ABC, ∫ BAC = 60 ° and the intersection of AD, be and CF at the point o. ∫ bea = 90 °, ∫ CFA = 90 °, ∫ Abe = 30 °, ∫ ACF = 30 °, ∫ OBD + ∫ OCB = 180 ° - ∫ BAC - ∫ OBD - ∫ OCD = 60 °, so, ∫ BOC = 180 ° - 60 ° = 120 °

In △ ABC, ∠ a = 70 °, the bisectors BD and CE of △ ABC intersect at point O, then ∠ BOC=______ Degree

If ∵ BD bisects ∵ ABC, ∵ 4 = 12 ∵ ABC, if CE bisects ∵ ACB, ∵ 2 + ∵ 4 = 12 (∵ ABC + ∵ ACB) = 12 (180 ° - a) = 12 (180 ° - 70 °) = 55 °, in △ BOC, ∵ BOC = 180 ° - 55 ° = 125 °

As shown in Figure 9, given that the bisectors BD and CE of △ ABC intersect at point O, the angle BOC = 100 ° and the degree of angle a is calculated
Come on, thank you

Do it with circle. In fact, it should be both sides of the vertical line? If the angle bisector can only do inscribed circle

As shown in the figure, in △ ABC, two bisectors BD and CE intersect at point O. if ∠ BOC = 116 °, then the degree of ∠ A is______ ．

As shown in the figure, ∵ BOC = 116 °, ∵ 1 + ∵ 3 = 180 ° - ∵ BOC = 180 ° - 116 ° = 64 ° while dB and EC divide ∵ ABC and ∵ ACB equally, ∵ 1 = ∵ 2, ∵ 3 = ∵ 4, ? 1 + ∵ 2 + ∵ 3 + ∵ 4 = 2 × 64 ° = 128 ° and ∵ a = 180 ° - (? 1 + ? 2 + ? 3 + ? 4) = 180 ° - 128 ° = 52 ° respectively

In △ ABC, the line of high BD and CE intersects at point O. if △ ABC is not a right triangle and ∠ a = 60 °, then ∠ BOC=______ ．

If ∠ BOC is within △ ABC, as shown in the following figure: ∵ BD and CE are the heights of △ ABC, ∵ BOC = 360 ° - ∵ a - ∵ ADO - ∵ AEO = 120 °; if ∵ BOC is outside △ ABC, as shown in the following figure: ∵ BD and CE are the heights of △ ABC, ∵ BOC = 90 ° - ∵ DCO = 90 ° - ∵ ace = 60 °. So the answer is: 120 ° or 60 °