"After listening to this story, I laugh at the same time"

"After listening to this story, I laugh at the same time"

I'll just add a men after the word
Hope to adopt

"Students sitting in the wide reading room reading" where is wrong? What is the cause?

Replace broadness with spaciousness

The students are sitting in the wide reading room reading books?

Wide to spacious

In the space rectangular coordinate system, there are three points a (5, - 4,1), B (3,2,1) C (2, - 5,0)

The lengths of AB, BC and AC are calculated respectively. The results show that ab square = 40, BC square = 51 and AC square = 11. According to Pythagorean theorem, a triangle is a right triangle

It is known that cos (2 α - β) = 1 / 5
Given that cos (2 α - β) = 1 / 5, sin α = (2 radical 2) / 3, and obtuse angles α and β are obtuse angles, the value of COS (α - β) can be obtained

cos（α-β）
=cos[（2α-β）+α]
=cos(2α-β)cosα-sin(2α-β)sin(α)
=(1 / 5) * (- 1 / 3) - (2 root 6 / 5) * (2 root 2) / 3
=-1 / 15 - (8 root 3) / 15

The following statement is correct ()
A. Two numbers with different symbols are called opposite numbers B. the opposite number of an integer is a fraction C. the opposite number of a non negative number is a non positive number D. the opposite number of a number must be negative

A, e.g. + 3 and - 4 have different symbols, but they are not opposite numbers; B, the opposite number of integer 2 is - 2, and - 2 is not a fraction; C, the opposite number of non negative numbers is non positive, which is correct; D, 0 and the opposite number of negative numbers are non negative, so select C

How to put forward the negative one of the base a? It's going to school soon. Is it written as log2 (5)
How to put forward the negative one of the base a? It's going to school soon. Is it written as log2 [(5) ^ - 1]

Write clearly. You should use brackets when you need to

(2010, Anhui) as shown in the figure, the similarity ratio of △ ABC ∽ a1b1c1 is K (k > 1), and the three side lengths of △ ABC are a, B, C (a > b > C), and the three side lengths of △ a1b1c1 are A1, B1, C1
(1) If C = A1, prove: a = KC; (2) if C = A1, try to give a pair of △ ABC and △ a1b1c1, so that a, B, C and A1, B1, C1 are positive integers, and explain; (3) if B = A1, C = B1, is there △ ABC and △ a1b1c1, so that k = 2? Please give reasons

(1) It is proved that: ∵ ABC ∽ a1b1c1, and the similarity ratio is K (k > 1), ∵ Aa1 = k, a = KA1; and ∵ C = A1, ∵ a = KC; (2) take a = 8, B = 6, C = 4, at the same time take A1 = 4, B1 = 3, C1 = 2; at this time, Aa1 = BB1 = CC1 = 2, ∵ ABC ∽ a1b1c1 and C = A1; (3) there is no such △ ABC

Why can the relationship between points, lines and surfaces be represented by set symbols

Because set is used to represent affiliation, point belongs to line, line belongs to face, so of course it can be represented by set

What is a double syllable

It is also called two spelled syllables. It is a syllable composed of an initial and a non intermediate vowel (the initial does not contain I, u and ü). It mainly includes the following: De, Shi, Yi, Bu, you, Zhi, Le, Ji, Zhe, wo, Ren, Li, TA dao.zhong 、zi、guo、shang、ge、men、he、wei、ye、du、go...