Given a (1,5), B (- 1,1), (3,2), if the quadrilateral ABCD is a parallelogram, find the coordinates of point D

Given a (1,5), B (- 1,1), (3,2), if the quadrilateral ABCD is a parallelogram, find the coordinates of point D

Let D (x, y)
Then AB = (- 2, - 4) CD = (x-3, Y-2)
AC=(2,-3) BD=(x+1,y-1)
AB is parallel to CD, AC is parallel to BD
So (- 2) / (x-3) = (- 4) / (Y-2) 2 / (x + 1) = (- 3) / (Y-1)
D = (1, - 2)

In known quadrilateral ABCD, ∠ A: ∠ B = 7:5, ∠ a - ∠ C = ∠ B, ∠ C = ∠ d-40 °. Find the degree of an internal angle?

Let a = 7x, B = 5x, C = 2x, d = 2x + 40 degrees
Then 7x + 5x + 2x + 2x + 40 = 360
We get x = 20
Therefore, the values of a, B, C and D are 140 degrees, 100 degrees, 40 degrees and 80 degrees respectively

Given the points a (1,0) B (5, - 2) C (8,4) d (4, - 6), it is proved that the quadrilateral ABCD is a rectangle

|Ab | = √ (5-1) ^ 2 + (0 + 2) ^ 2 = 2 √ 5 | BC | = √ (8-5) ^ 2 + (4 + 2) ^ 2 = 3 √ 5 | ad | = √ (4-1) ^ 2 + (0 + 6) ^ 2 = 3 √ 5 | AC | = √ (8-1) ^ 2 + (4-0) ^ 2 = √ 65 | CD | = √ (8-5) ^ 2 + (4 + 2) ^ 2 = 3 √ 5 because AB = CD, ad = BC, the quadrilateral is parallelogram, because AB ^ 2 + BC ^ 2 = 65 = AC ^ 2, so

Connect four points a (- 4,3), B (2,5), C (6,3), D (- 3,0) in order to judge the shape of quadrilateral ABCD

Kab=1/3
Kbc=-1/2
Kcd=1/3
Kad=-3
So the line ad is perpendicular to the lines AB and CD
And the line BC is not parallel to any line
So it's a right angled trapezoid

In the plane rectangular coordinate system: a (0, - 4) B (- 2.0) C (6,4) d (8,0)
Can not be specific process, to clear thinking

Rectangle
First of all, draw pictures and combine figures with figures
Using Pythagorean theorem
AB = CD = 2 times root 5
BC = ad = 4 times root 5
The quadrilateral ABCD is a parallelogram
∵AC=10
∴AB²+BC²=AC²
∴∠ABC=90°
The quadrilateral ABCD is a rectangle

Four points a (1,2), B (4,0), C (8,6), D (5,8) are known to judge the shape of the quadrilateral ABCD

AB = CD
BC = ad
Two groups of quadrilaterals with equal sides are parallelograms

A (- 1,0) B (0,2) C (5,5) d (3,1) judging quadrilateral ABCD shape
RT, thank you

It is to judge the slope of four lines and the length between points. (it is a simple two-point length formula, which can't be written as ^ (1 / 2) ((XA XB) ^ 2 + (Ya Yb) ^ 2) ^ (1 / 2) AB length = (- 1-0) ^ 2 + (0-2) ^ 2) ^ (1 / 2) = 2.23bc length = ((0-5) ^ 2 + (2-5) ^ 2) ^ (1 / 2) = 5.83cd length = ((5-3) ^ 2 + (5-1) ^ 2) ^ (

Given a (- 3,3), B (- 5, O), C (5,0), D (3,5), find the area of quadrilateral ABCD

This figure can be divided into two triangles and a trapezoid, in the area, the area is 32

Char * AA [2] = {"ABCD", "ABCD"}; how to explain this sentence?
It is defined as follows:
char *aa[2]={"abcd","ABCD"};
The following statement is true
A. Aathe values of array elements are "ABCD" and "ABCD" respectively. B.aa is a pointer variable, which points to a character type one-dimensional array containing two array elements
C. The two elements of the AA array store the first address of the one-dimensional character array with four characters respectively. The two elements of the d.aa array store the addresses of the characters' a 'and' a 'respectively

This statement defines a string array pointer AA with 2 elements
AA [0] points to the address to store "ABCD"
AA [1] point to the address to store "ABCD"

In the quadrilateral ABCD, ∠ d = 60 °, the value of ∠ B is 20 ° larger than that of ∠ a, and the value of ∠ C is 2 times of that of ∠ a

Let a = x, then B = x + 20 ° and C = 2x. The theorem of sum of internal angles of quadrilateral obtains x + (x + 20 °) + 2x + 60 ° and 360 ° respectively, and the solution is x = 70 °. A = 70 °, B = 90 ° and C = 140 °