13 questions, thank you, 13 questions, thank you?

Proof: Because the quadrilateral abcd is a square, the angle dab angle abc = 90 degrees, da = ab = ac

Because the triangle cde is an equilateral triangle, the angle eab angle eba is 60 degrees, ea=ab=eb

So the angle dae angle cbe 30 degrees, da=ae eb=bc (indicating that the triangle ade and triangle ebc are isosceles triangles).

So the angle ade angle aed angle ceb = angle bce 75 degrees.

So the angle dec 360-75-75-60 = 150 degrees.

abcd is a square and abe is an equilateral triangle.

ad=ab =bc =ae=be

eab=∠ebc =60=∠aeb

dae =∠cbe =30

ad＝ae ，bc =be

dea =1/2(180-30)=75

ceb =1/2(180-30)=75

dea+∠ceb+∠aeb+∠dec =360∠dec=360-60-75-75=150

The triangle abe is an equilateral triangle, then ab=ae=be=bc=ad, angle eac=angle ebc=angle aeb=60 degrees;

And the angle abc = 90 degrees, so the angle ebc = 30 degrees.

Since the triangle EBC is an equilateral triangle, the angle BEC = angle BCE = 75 degrees, in the same way, the angle AED = 75 degrees, so the angle DEC = 360 degrees - angle AEC - angle AED = 360 - 60 - 75 - 75 = 150 degrees.

Solution: Because ABCD is a square, the angle DAB = 90 degrees, because ABE is an equilateral triangle, the angle EAB = 60 degrees, the angle DAE = angle DAB - Angle EAB = 90 degrees - 60 degrees = 30 degrees.

Set the angle DCE to X, and a simple formula will come out according to the circumferential angle and the 360 triangle inner angles and 180 columns.

(1) Because AD=BC, the inferior arc AD=Inferior arc BC is reduced on both sides of the arc AC, so the arc AB=arc CD, so AB=CD

2) Because the circumferential angles of the equal arcs are equal, the two base angles are equal, so ae=ce

<> remember my fire-resistant answer, I wish you Chang Nianxu to learn and make progress.

The original plan was to complete the slag eggplant into x sets of schools every day, so that the ruler clothes were like a slippery inspection.

3000 x = 4 + 3000 (1 + 20%) x

The solution is x=125