In equilateral triangle ABC, if points E and D are on AB and AC respectively, and EB = ad, BD and EC intersect point F, then ∠ DFC= To prove

In equilateral triangle ABC, if points E and D are on AB and AC respectively, and EB = ad, BD and EC intersect point F, then ∠ DFC= To prove

60 degrees

How many square decimeters is one hectare equal to?

One hectare is equal to one million square decimeters

The upper bottom of trapezoid is 20 cm, the lower bottom is 30 cm, and the area of shadow part is 300 square cm

300 × 2 △ 30 = 20 cm (H)
Trapezoid area = (20 + 30) × 20 △ 2 = 500 square centimeter
I wish you progress in your study!
If you don't understand, please ask. If you understand, please adopt in time! (*^__ ^*)

If the sum of the perimeter of the new triangle and the original triangle is 60, then the perimeter of the original triangle is ()
A.20 B.30 C.40 D 50

The new triangle is similar to the original triangle, and the similarity ratio is 1 / 2
The perimeter ratio of the new triangle to the original triangle is 1 / 2
So the perimeter of the new triangle is 60 (1 + 2) = 20, and the perimeter of the original triangle is 20 * 2 = 40

How to answer the square of [(2a + b) △ 2] - [(2a-b) △ 2]

Square of [(2a + b) × 2] - square of [(2a-b) × 2]
=[(2a+b)÷2-(2a-b)÷2]*[(2a+b)÷2+(2a-b)÷2]
=b*2a
=2ab

Look at the picture and guess the idiom. There is a circle on the left and a dunhao on the right. What idiom is it?

It's remarkable

Science
There are two electric heating wires with the same resistance. They are connected in series with a certain power supply. The two sections heat a pot of cold water and can be boiled in 10 minutes. If they are connected in parallel, it will take several minutes

Five minutes
Let the resistance of each section be r
Series resistance: 2R
Series power: U / 2R
Parallel resistance: the reciprocal of (1 / R + 1 / R), i.e. R / 2
Parallel power: U / (R / 2)
The ratio is equal to 1 / 4

When x = 2, the value of the algebraic expression ax ^ 5 + BX ^ 3 + cx-2 is 0. When x = - 2, find the value of the algebraic expression

More questions, less answers:
When x = 2,
ax^5+bx^3+cx-2
=32a+8b+2c-2
=0
That is 32A + 8b + 2C = 2
When x = - 2,
ax^5+bx^3+cx-2
=-32a-8b-2c-2
=-(32a+8b+2c)-2
=-2-2
=-4

There is a rectangular experimental field 250 meters long and 100 meters wide. How many centimeters should we draw the agricultural planning map with the scale of 1:5000?

250 * 100 = 25000 (CM)
100 * 100 = 10000 (CM)
25000 / 5000 = 5 (CM)
10000 / 5000 = 2 (CM)
A: the length should be 5cm and the width should be 2cm
This question is too simple. Did you listen carefully in class

Spring outing in Luoxingta Park and Mawei shipyard
To Mawei → visit the shipyard → watch the process of shipbuilding → visit Mawei shipbuilding history museum → visit Zhaozhong temple → visit Luoxing Tower Park. No history and legend!

As soon as we entered the museum, we were stunned by a piece of bronze sculpture in front of us. Walking on the blue gray marble ground, I felt the breadth and profundity of Mawei Shipping culture, realized the "grand ideal" of the Chinese nation, and was deeply educated. It made me understand that only with strong military strength as the backing can we strengthen and enrich the country!