As shown in the figure, for a square with a side length greater than 4cm, draw a line along the 45 ° angle 2cm away from the four vertices of the square, and divide the square paper into five parts, then the area of the middle shadow part is______ cm2．

As shown in the figure, for a square with a side length greater than 4cm, draw a line along the 45 ° angle 2cm away from the four vertices of the square, and divide the square paper into five parts, then the area of the middle shadow part is______ cm2．

As shown in the figure, lengthen one side ab of the small square, intersect with one side of the large square at point C, connect CD, ∧ CED is an isosceles right triangle with right angle side length of 2cm, ∧ CD = de2 + CE2 = 8 = 22, ∧ side length of shadow square = ab = 22, ∧ area of shadow Square: 22 × 22 = 8 (cm2). So the answer is: 8

If the height of an isosceles triangle is equal to half the waist length, what is the base of the isosceles triangle

Let the base angle be a
Then: Sina = height / waist length = 1 / 2
So a = 30 degrees, that is to say, the base angle of this isosceles triangle is 30 degrees

It is known that: as shown in the figure, in the trapezoidal ABCD, ab ‖ DC, ∠ B = 90 °, BC = 8cm, CD = 24cm, ab = 26cm, point P starts from C and moves to D at the speed of 1cm / s, point Q starts from a and moves to B at the speed of 3cm / S. & nbsp; when one of the moving points reaches the end point, the other stops moving. From the beginning of the movement. (1) how long does it take for a quadrilateral aqpd to be a parallelogram? (2) How long does it take for a quadrilateral aqpd to become an isosceles trapezoid? (3) Is it possible for P, Q, B and C to form a square in motion? Why?

Let P and Q move for T seconds, then PC = TCM, AQ = 3tcm (1) when DP = AQ, the quadrilateral aqpd is a parallelogram, that is, 24-t = 3T, the solution is t = 6, a: after 6 seconds, the quadrilateral aqpd is a parallelogram. (2) DM ⊥ AB over D is m, PN ⊥ AB over P is n, ∫ quadrilateral aqpd is an isosceles trapezoid, ∧ am = Q

In RT △ ABC, 90 ° ACB, D, e and F are the midpoint of AB, BC and AC respectively. The relationship between EF and CD is judged and the reason is explained
Illustration: B on the left, C on the right, upper a, point e at the midpoint of BC, point F at the midpoint of AC, and point d at the midpoint of ab,

Because the center line on the hypotenuse of a right triangle is half of the hypotenuse
So CD = 1 / 2Ab
Because e and F are the midpoint
So EF is the median line
So EF = 1 / 2Ab
So CD = EF

Rotate one circle along one right side of a right triangle. The figure produced by the rotation of the triangle is
A. Triangle B, circle C, cone D, cylinder

Cone D

Analysis of scientific principles (58:56:53)
Please analyze the scientific principle of "sharpening the knife does not miss the firewood cutter"

Grinding will make the contact area smaller, in the case of the same pressure, the effect of pressure, that is, the pressure increases with the decrease of contact area!

What's the answer to question 2 on page 11 of science exercise book B for Grade 7?

u=v
(1)15cm
(2) The real image of handstand reduction
(3) Inverted enlarged real image
(4) The virtual image of upright magnification
(5) Away from lens B
That's it. I made it myself

After they meet, the speed of a decreases by 20%, and the speed of B increases by 20%. Finally, B arrives at the destination first. When B arrives, a is still 20 kilometers away from the destination
Is it 1100km

6×（1-20%）=4.8
5×(1+20%)=6
4.8:6=4:5
6+5=11
6/11÷5×4=24/55
20 ÷ (5 / 11-24 / 55) = 1100 (km)

Ask everybody a primary school sixth grade mathematics
The actual height of No.1 building in Yuxin community is 35 meters, and the ratio of its height to the height of the model is 500:1?
35m = 3500 cm
Is his answer 3500: x = 500: 1 or 500: 1 = 3500: X or both?

It doesn't matter if you replace both sides of the equation. It's all right

Application of percentage
The year before last, the annual interest rate of fixed deposit in the bank was increased to 2.25% in one year and 2.7% in two years. Jiajia's father deposited 100000 yuan in the bank in the following two ways. Which way can he get more interest in two years? How much more yuan? (the interest rate is 20%)
Method a: according to the two-year interest rate, deposit for two years, and withdraw when due;
Method B: according to the one - year interest rate, deposit for one year, and then transfer the capital and interest for one year
Need specific process, 90 ° bow

Method a interest: 100000 × 2.7% = 2700 yuan, after tax interest: 2700 × (1-20%) = 2160 yuan, method B interest: 100000 × 2.25% = 2250 in the first year, after tax interest: 2250 × (1-20%) = 1800 in the second year, 101800 × 2.25% = 2290.5, after tax interest: 2290.5 × (1-20%) = 1832.4 yuan