In the triangle ABC, CD is the middle line on the edge of AB, and Da = DB = DC Verification angle ACD = 90 degree

Because Da = DB = DC
So ∠ a = ∠ ACD, ∠ B = ∠ DCB
Because ∠ a + ∠ ACD + ∠ B + ∠ DCB = 180 ° i.e. 2 (∠ ACD + ∠ DCB) = 180 ° i.e. 2 ∠ ACD = 180 °
∠ACD=90°

Given a (- 1,2), B (2,8) (1) if vector AB = 3 / 1 vector AB, vector Da = - 3 / 2 vector AB, find the coordinates of vector CD

If a (- 1,2), B (2,8) (1) if the vector AC = 1 / 3, the vector AB, the vector Da = - 3 / 2, the vector AB, find the coordinates of the vector CD. (even if it's not like this, read the following solution, I think you can solve it yourself.)
Let C (x, y), D (m, n), then vector AC = (x + 1, Y-2), vector AB = (3,6), from x + 1 = (1 / 3) * 3 = 1, Y-2 = (1 / 3) * 6 = 2, we can get x = 0, y = 4, so C (0,4), vector Da = (- 1-m, 2-N) = (- 3 / 2) * (3,6) = (- 9 / 2, - 9), so - 1-m = - 9 / 2, 2-N = - 9, so m = 7 / 2, n = 11, so D (7 / 2,11), so vector CD = (7 / 2,7)

Given a = (- 1,2) B = (2,8) and vector AC = one-third times vector AB, vector Da = negative one-third times Ba, we can find the coordinates of point C

AB=(3,6),AC=1/3(3,6)=(1,2),C=A+AC=(0,4)

Given the point a (- 1,2), BA (2,8), vector AC = 1 / 3AB, vector Da = - 1 / 3ba, find the coordinates of point C, D and vector CD

OA = (- 1,2), OB = (2,8),
Because AC = 1 / 3 * AB, oc-oa = 1 / 3 * (ob-oa),
The solution is OC = 1 / 3 * ob + 2 / 3 * OA = (2 / 3,8 / 3) + (- 2 / 3,4 / 3) = (0,4), namely C (0,4);
From Da = - 1 / 3 * Ba, oa-od = - 1 / 3 * (oa-ob),
So od = 4 / 3 * oa-1 / 3 * ob = (- 4 / 3,8 / 3) + (- 2 / 3, - 8 / 3) = (- 2,0), namely D (- 2,0)

(1) If you want to lay the same size glass on the desktop, how many square meters is the area of this glass? (2) How many meters will it take if a metal strip is inserted around the desktop?

(1) 3.14 × (2 △ 2) 2, = 3.14 × 1, = 3.14 (square meters); a: the area of the desktop glass is 3.14 square meters. (2) 3.14 × 2 = 6.28 (meters); a: if the metal strip is set around the desktop, it needs 6.28 meters

The bedroom area is 11.5 square meters, 4 meters long from north to South and 2.85 meters wide from east to west. I want to put a 1.8 * 2 meter bed, a 1.6 meter long wardrobe and a desk,
The bed and two bedside tables are nearly three meters wide. The bed wants to be placed in the east-west direction, and the wardrobe wants to be placed against the south wall. Where is the desk? Will it be a bit crowded?

If you can put it down, you can put the desk close to the window and the wall. It's about 1.2 meters long, then the bed is 1.8 meters long, and then the bedside table is 500 meters long. If you put the rest of the wardrobe along the wall, you can put it down

A student estimates that the area of the atmosphere is 0.27 square meters, and the pressure on the surface of the desk is about () n
A2.710^2N B2.710^3N C2.710^4N D2.710^5N

Answer: C
Analysis: the atmospheric pressure is about 1000000pa
Pressure: F = PS = 100000 × 0.27 = 27000n
C is correct
I don't know what to ask

How is the price of density board calculated by square
50 yuan per sheet, the length of the board is 2.4 meters, the width is 1.2 meters, and the thickness is 0.9 meters
If how to calculate a cabinet, the length, width and height of the cabinet are 38 * 15 * 45
What is the price of this cabinet? What is the specific calculation process?

The first question: 50 yuan (2.4 m × 1.2 m) = 17.36 yuan / m2. The second question, because the conditions given are not clear, can not be answered

The unit price of the album is 16 yuan per square meter, which is 1.1 * 1 meter in length and 1 meter in width

1.1 * 1 = 1.1 (M2)
16 * 1.1 = 17.6 yuan

How does density board calculate price by square
How is the price of density board calculated by square
50 yuan a board, the length of the board is 2.4 meters, the width is 1.2 meters, the thickness is 0.9 meters
35 * 14cm = what's the price

Large plate can be cut to about 50 pieces. Considering the processing cost, about 1.5 yuan per piece

In the triangle ABC, CD is the middle line on the edge of AB, and Da = DB = DC Verification angle ACD = 90 degree