As shown in the figure, in the isosceles triangle ABCD, AD / / BC, point E is a point on the extension line of AD, de = BC

As shown in the figure, in the isosceles triangle ABCD, AD / / BC, point E is a point on the extension line of AD, de = BC

It should be isosceles trapezoid. If it is, then both of them will work
(1) By de = BC and de ‖ BC,
The quadrilateral DECB is a parallelogram (two opposite sides are parallel and equal),
Then EC = dB (similarly)
And because AC = dB (the two diagonals of isosceles trapezoid are equal)
So AC = EC (equivalent substitution)
So △ ace is isosceles triangle
(2) Connect CE, AC according to the drawing
ABCD is isosceles trapezoid,
∴∠ABC=∠BCD.
And ∠ BCD = ∠ CDE (the internal stagger angles of parallel lines are equal),
AB=CD.∠ABC=∠CDE.
△ABC≌△CDE (SAS)
∴AC=CE.
The ace is an isosceles triangle

Sixth grade mathematics problem 1, can calculate simply, 2, solve the equation (are fractions)
1、 Simple calculation
2 and 2 / 3 ／ 5 ／ 4 / 15 2 and 1 / 2 ／ 1 / 4 × 1 and 2 / 3 5 / 7 ／ 1 and 1 / 14 ／ 3 7 / 12 × 2 / 3 ／ 7 / 8 2 and 1 / 5 × 1 and 2 / 3 ／ 5 and 1 / 2
2 and 2 / 3 △ 6 × 3 and 3 / 8
2、 Solving the equation
1 / 3x × 4 / 9 = 1 / 6 4x × 7 / 10 = 7 / 20 2 / 3x × 1 and 1 / 14 = 5 / 7 7x △ 1 / 2 = 3 / 5
Ah ah ah, I can't stand the sixth grade problem. The tutor didn't say much about it. I can't understand it. I want to ask the big God to solve my homework. I'm in a hurry!
I'm going to hand it in this afternoon. I'm in grade five!

For example: 1 original formula = 8 / 3 × 1 / 5 × 15 / 4 = 2 × 1 × 1 = 2, because divided by a number = multiplied by the reciprocal of a number
If you want to solve the equation, you have to divide it first and then solve it
Hope to adopt, thank you

Given that y = f (x) is an even function and a decreasing function on (0, positive infinity), judge whether f (x) is an increasing function or a decreasing function on (negative infinity, 0) and prove

Increasing function
prove:
It is known that y = f (x) is an even function
So f (x) = f (- x)
On (negative infinity, 0), let x 10 be arbitrary
So f (- x1)

Draw the largest square in a circle with a radius of 4 decimeters. What is the area of the square in square decimeters?

It is known from the analysis that the two diagonals of the square divide the whole square into four equal isosceles right triangles. The bottom and height of each isosceles right triangle are 4cm, so the area of the square is: 4 × 4 △ 2 × 4 = 8 × 4 = 32 (square centimeter). A: the area of the square is 32cm

I just want to know how much DM is equal to 1nm and how much nm is equal to 1cm and how much cm is equal to 1um

0.000000001 10000000 0.0001

A toy factory advertised: "our factory workers work 8 hours a day, 25 days a month; treatment: skilled workers work by piece."
Fast forward!
According to the advertisement of a toy factory, "the working hours of the workers in our factory are 8 hours a day and 25 days a month; the treatment is that the skilled workers pay by piece, more work, more pay, the piece rate is not less than 800 yuan, and the welfare wage is 100 yuan per month, which is settled by month." The factory produces only two kinds of toys: dogs and cars. Xiaoyun, a skilled worker, gets a monthly salary of more than 900 yuan. She records some data in the following table:
Number of puppies number of cars total time (minutes) total salary (yuan)
1 1 35 2.15
2 2 70 4.30
3 3 85 5.05
There is no limit on the number of puppies and cars to be produced in January. From February, the factory adjusted the number of puppies and cars to be produced by each worker every month (k = 2,...) 12) Assuming that Xiaoyun's work efficiency remains unchanged and obeys the factory's arrangement, please use the mathematical knowledge to explain whether the manufacturer's advertisement is fraudulent?
Number of puppies number of cars total time (minutes) total salary (yuan)
－－－－－－－1－－－－－－－1－－－－－－－35－－－－－－2.15
－－－－－－－2－－－－－－－2－－－－－－

Analysis: according to the second and third lines of the statistics, it takes 15 (= 85-70) minutes to make a dog, and the salary is 0.75 (= 5.05-4.30) yuan. According to the first line, it takes 20 (= 35-15) minutes to make a car, and the salary is 1.40 (= 2.15-0.75) yuan. The monthly working time is 60 × 8 × 25 =

The perimeter of a rectangle is 48 decimeters. If the width was increased by 2 decimeters and the length remained unchanged, and the area increased by 16 square decimeters, what was the width of the original rectangle?
It's a formula. Thank you!

If the width was increased by 2 decimeters and the length remained unchanged, the area would be increased by 16 square decimeters,
So the original length = 16 / 2 = 8 decimeters
Therefore, the original width = 48 / 2 - 8 = 16 decimeters

What's the rule of 3 6 9 12 15 21?

The sum of the first two numbers equals the fourth number

It takes three minutes for a train to cross the 2440 meter bridge. It takes only one minute for a train to pass by a power pole at the same speed
Does this train run every minute?

Length of train + length of bridge = length of train * 3
Length of bridge = length of train * 2
Length of train = 2440 / 2 = 1220 M
The train runs 1220 meters per minute

It is known that the perimeter of a large rectangle is 38 cm, and the shadow part is a square. Find the length and width of the large rectangle

38 △ 2 = 19cm, width: 19 △ 2 = 8cm, 8 △ 4 = 2cm, length: 19-2 = 17cm