Judge whether the following propositions are true or false, and give reasons (1) If a + B + C = 180 °, then a, B and C must be the three inner angles of the triangle (2) If a ∩ B ≠ &;, B is really contained in C, then a ∩ C ≠ &;

False does not say the problem of triangles
2. If a ∩ B ≠ &;, there exists X
Let x ∈ a, X ∈ B,
If B is really contained in C, then x ∈ C,
So a ∩ C ≠ &; (x ∈ a ∩ C)
It's an empty collection upstairs

Judge the truth of the following propositions and give reasons
The value of the algebraic formula x ^ 2-4x + 5 is greater than or equal to 1

X ^ 2-4x + 5 = (X-2) ^ 2 + 1 is obviously greater than or equal to 1. Therefore, the proposition given is true

Judge whether the following propositions are true or false, and give reasons
(1) A middle line of a triangle divides the triangle into two parts of equal area
(2) The difference between an obtuse angle and an acute angle is an acute angle

(1) Basic facts of true proposition
(2) Examples of false proposition: 120 degrees (obtuse angle) - 30 degrees (acute angle) = 90 degrees (right angle)

Xiaoming and Xiaogang run 100 meters (assuming the same speed). When Xiaogang runs 90 meters, Xiaoming is 25 meters away from the finish line. When the trot is complete, how many meters is Xiaoming away from the finish line?

100-100 * 75 / 90 = 16.67m from the end point

If there are three continuous natural numbers and the middle one is a, then the two natural numbers before and after are () and (), and the sum of these three numbers is ()
If there are three continuous natural numbers and the middle one is a, then the two natural numbers before and after are () and (), and the sum of these three numbers is ()

The front one is A-1
And then there's a + 1
And it's 3a

How do 10, 9, 3, 1 Equal 24

(10+1)*3-9=24

Below is a 24 cm long and 12 cm wide rectangular iron sheet. Can you cut it into five pieces and weld it into a rectangular container with a square bottom? (no waste of materials) (draw a picture of the scissors)
Calculate: what's the volume of this container? Urgent! Urgent!

If the volume is not required, simply cut it. The volume is 12 × 12 × 3 = 432

A table is 40 yuan more expensive than a chair. A table is five thirds of the price of a chair?

Chair = 40 (5 / 3-1) = 60 yuan
Table = 60 + 40 = 100 yuan
Do not understand can ask, help please adopt, thank you!

Unit conversion with fraction, 89 minutes = [hours], 3140 meters = [kilometers], 123 centimeters = [meters], 1911 square decimeters = [square meters]

Unit conversion with fraction, 89 minutes = [1:29] hours, 3140 meters = [3.14] kilometers, 123 centimeters = [1.23] meters, 1911 square decimeters = [19.11] square meters

There are 13 Science and technology books in our bookcase, half of them are story books, and the rest are comic books. How many are comic books?

1-13-12, = 23-12, = 16

Judge whether the following propositions are true or false, and give reasons (1) If a + B + C = 180 °, then a, B and C must be the three inner angles of the triangle (2) If a ∩ B ≠ &;, B is really contained in C, then a ∩ C ≠ &;