In quadrilateral ABCD, ad = BC, AE, CF are perpendicular to BD, be = DF. It is proved that quadrilateral ABCD is parallelogram I can't find the last condition in the verification. Please give me some advice. Thank you

DF=BE
DF + EF = be + EF is BF = De, and angle AED = angle CFB = 90 degrees
Ad = CB, so triangle BFC is congruent with triangle DAE,
So, the angle ADB = CBD, the internal stagger angle is equal, so ad is parallel to BC, because ad = BC, ad and BC are parallel and equal
So the quadrilateral ABCD is a parallelogram

The quadrilateral ABCD is a parallelogram. The points E and F are on the straight line BC. What is the quantitative relationship between AE ‖ BD, AC ‖ DF, ad and ef

AD=1/3EF
prove:
∵ AD / / BC, namely AD / / be,
AE / / BD,
The quadrilateral ADBE is a parallelogram
∴AD=BE；
Similarly, ad = CF
∴AD=1/3EF
It's over

As shown in figure (1), in square ABCD, point h starts from point C and moves along CB to stop at point B. connect diagonal AC of DH intersection square to point E, and make vertical intersection AB and CD of DH at points F and G through point E. (1) prove DH = FG; (2) in figure (1), extend intersection of FG and BC to point P, connect DF and DP (as shown in figure (2)), try to explore the relationship between DF and DP, and explain the reason

(1) It is proved that: as shown in Fig. 1, FP is perpendicular to DC through point F, and the vertical foot is p, ∠ FPD = 90 °, ∫∠ bad = ∠ ADC = ∠ FPG = 90 °, the quadrangle afpd is rectangular, ｜ ad = FP, ∫ eg ⊥ DH, ∫ 1 + ∠ 2 = 90 °, ∫ 3 + ∠ 4 = 90 °, ∫ 1 = ∠ 4, ∫ 2 = ∠ 3, ∫ FPG = ∠ BCD, FP = CD

Symmetric graph of quadrilateral ABCD with respect to o point

The method of drawing symmetric points is to take a ruler, find an integer position on the ruler, align o point, one end of o point to a point, observe the distance from a point to o point, such as 2cm, then at the other end of o point, use

How to enlarge the quadrilateral ABCD to twice its original size, that is, drawing. Please draw a picture,

Method:
1) Extend Ba to a & # 39;, so that AA & # 39; = Ba,
Extend BD to D & # 39;, so that DD & # 39; = BD,
Extend BC to C & # 39;, so that CC & # 39; = BC,
2) Connect a & # 39;, D & # 39;, C & # 39;, and get quadrilateral A & # 39; BC & # 39; D & # 39;
A quadrilateral is twice the area of a quadrilateral ABCD

As shown in the figure, in rectangular ABCD, ab = 4cm, ad = 12cm, point P moves from a to D at the speed of 1cm per second on the side of AD, point Q moves from point C at the speed of 4cm per second on the side of BC, and moves back and forth between CB. Two points start at the same time. When point P reaches point D, when t = () s, the line segment pq||ab

I've worked it out for you. The correct answers are: 4.8, 8, 9.6 and 16.6
Let me just talk about the first one for you, and think about the rest by myself, OK? To make PQ parallel to AB, you should make AP = BQ, you should understand? The speed of P point is 1cm / s, then after t s, the length of AP should be t cm, q point is fast, you must reach C point and then return to B point to make PQ parallel to AB, understand? Q point takes 3S from B point to C point, then after t s, The length of BQ should be 12-4 (T-3), do you understand? The equation t = 12-4 (T-3), the solution t = 4.8. You can think about the remaining three answers by yourself, the idea is almost the same, and it's too troublesome for me to tell you again. This is a difficult problem, I advise you to do a simple problem first, lay a good foundation, and then do this kind of problem

In rectangular ABCD, ab = 4cm, ad = 12cm, point P moves from point a to point d at the speed of 1cm per second on the edge of AD
As shown in the figure, in rectangular ABCD, ab = 4cm, ad = 12cm, point P moves from point a to point d at the speed of 1cm / s, Q starts from point C at the speed of 4cm / s, and makes a round-trip motion between two points B and C. two points start at the same time, and point P reaches point D. during this period, line segment PQ is sometimes parallel to line segment ab

I've worked it out for you, and the correct answer is: 4.8, 8, 9.6 and 16. So I think it's four times. I'll just tell you the first one, and use my brain to think about the rest, OK? To make PQ parallel to AB, you should make AP = BQ, which you should understand? The speed of P point is 1cm / s, then after t s, the length of AP should be t cm, Q point

In square ABCD, ab = 2, e is the vertical bisector of a point be on ad intersecting AB at M intersecting DC at n. when the area of quadrilateral ADNM is the largest, the value of AE is?
Please draw a picture by yourself

In the quadrilateral ABCD, ad is parallel to BC, e is the midpoint of CD, connecting AE, be, be ⊥ AE

It is proved that the extension line of extended AE and BC intersects at point M. because ad is parallel to BC, angle EDA = angle ECM, angle ead = angle EMC, because e is the midpoint of CD, so de = CE, so triangle ade and triangle MCE are congruent (AAS), so ad = cmae = me, because be is vertical to AE, so angle AEB = angle MEB = 90 degrees, because be = be, so triangle Abe and

In the quadrilateral ABCD, point E is the midpoint of BC, point F is the midpoint of CD, and AE ⊥ BC, AF ⊥ CD

As auxiliary line AC, because AE and AF are both midline and vertical line, so triangle ABC and triangle ACD are isosceles triangle, so AB = AC = ad, so AB = ad

In quadrilateral ABCD, ad = BC, AE, CF are perpendicular to BD, be = DF. It is proved that quadrilateral ABCD is parallelogram I can't find the last condition in the verification. Please give me some advice. Thank you