Every time we look up at the flying five-star red flag, every time we sing the solemn national anthem, we feel excited

Every time we look up at the flying five-star red flag, every time we sing the solemn national anthem, we feel excited

What kind of quality is the grass singing life

It shows that Xiaocao loves life and is optimistic

When calculating the gram weight of cloth, who can tell me how to calculate the difference between the gram weight and the square meter?
Such as the title! Best to give an example, the more detailed the better

Square gram weight means the weight of 1 square meter cloth, which is measured in gram, not in kilogram or weight. 1 square meter intuitively means the area of a cloth or other plane with length and width of 1 meter. Of course, 2 meters long and 0.5 meters wide are also 1 square meter. For example, a cloth with length of 100 meters, width of 1.5 meters and square gram weight of 60 grams

The bottom of trapezoid is twice as big as the top. Please divide it into four shapes with the same size and shape! Isosceles trapezoid with 60 ° lower inner angle!

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Through two 120 ° angles, make angle bisector respectively, the original trapezoid upper bottom is & nbsp; small trapezoid lower bottom, the bisector of two angles is two waist, and the small trapezoid upper bottom is half of the lower bottom
(the rest is easy to do)

What are the axisymmetric figures in life? The more the better~
For example, tables and chairs. If there are more than 30, 50 points will be added~
Generally cylindrical, conical, cube, cuboid geometry are axisymmetric graphics, so there are cups (no handle), books, volleyball, football, basketball, badminton racket, cabinet, fan, stool, table, quilt, sofa, couplet, pencil box and so on in life
There are also airplanes, butterflies, pine trees, the logo of the Bank of China, the logo of the industrial and Commercial Bank of China, and the five pointed star on the five-star red flag. Don't say that

Mouse, mouse pad, monitor, schoolbag, tea table, glasses box, air conditioner, speaker, playground, plastic bag, Unicom logo, McDonald's logo, beverage bottle, blackboard, blackboard eraser, chalk, platform, pot, spatula, toilet paper, toilet, toothpaste, toothbrush, towel, nozzle, a pair of shoes, sun, moon, clothes, and most animals are symmetrical

Given x ^ 3 + x ^ 2 + X + 1 = 0, find the value of 1 + X + x ^ 2 + x ^ 3 +... + x ^ 2008 (to process)

1+x+x^2+x^3+...+x^2008
=1+x(1+x+x²+x³)+x^5(1+x+x²+x³﹚＋···＋x^2005(1+x+x²+x³﹚
=1+0+0+···+0
=1

Given nonzero vector a, find the module of vector 1 / A * a

The answer is 1

As shown in the figure, ab ⊥ BC, FA ⊥ AC, BC = 3cm, ab = 4cm, AF = 12cm, calculate the area of square cdef

According to Pythagorean theorem, AC = 53 square + 4 square = 25 and then square
Continue Pythagorean theorem to get CF = 13 12 square + 5 square = 169 square
Then according to the square area equal to the square of the diagonal divided by 2, cdef area = 84.5

Given the vector a = (x ^ 2, x + 1), B = (1-x, t), if the function f (x) = a × B, obtains the extremum at x = 1, then the value of T is

f(x)=x²(1-x)+(x+1)t
=-x³+x²+tx+t.
f'(x)=-3x²+2x+t
Because x = 1 is the extreme point, f '(1) = 0
So - 3 + 2 + T = 0, t = 1

How to prove that when three points are collinear, the sum of the coefficients before two vectors is equal to 1

Let a, B and C be collinear, and o be any point in the plane
Because a, B and C are collinear, there is a non-zero real number k such that
AB=kAC
Ob-oa = K (oc-oa)
So ob = Koc + (1-k) OA
[Note: two coefficients and K + 1-k = 1]
On the contrary, if there is a real number x, y satisfies x + y = 1, and OA = xob + yoc
Then OA = xob + (1-x) OC
OA-OC=x(OB-OC)
So CA = xcb
So the vector Ca and CB are collinear,
Because Ca and CB have a common point C
So a, B and C are collinear