As shown in the figure, the circumference of the circle is 25.12 cm, and the area of the circle is exactly equal to that of the rectangle. How long is the rectangle?

Radius of circle: 25.12 △ 3.14 △ 2 = 4 (CM), area of circle (area of rectangle): 3.14 × 42, = 3.14 × 16, = 50.24 (square cm); length of rectangle: 50.24 △ 4 = 12.56 (CM); answer: the length of rectangle is 12.56 cm

The circumference of a circle is 25.12 cm, and the area of a circle and a rectangle is equal?

The length of the rectangle is half of the circumference of the circle, 12.56 cm. The width is equivalent to the radius of the circle, which is 4 cm

Perimeter and area of square? Perimeter and area of rectangle? Area and perimeter of circle? Area of trapezoid? Area of triangle? Area of parallelogram
What is it?

Square: perimeter = side length X4 area = side length x side length
Rectangle: perimeter = (length + width) x2 area = length x width
Circle: perimeter = 2x3.14x radius area = 3.14x square of radius
Trapezoid: area = (upper bottom + lower bottom) x height / 2
Triangle: area = bottom x height / 2
Parallelogram: area = base x height

Given any quadrilateral ABCD, and the midpoint of AB, BC, CD, Da, AC, BD are e, F, G, h, P, Q respectively. (1) if quadrilateral ABCD is as shown in Figure 1, judge whether the following conclusions are correct (fill "√" in the brackets correctly, and "×" in the brackets wrongly). () a: connect EF, FG, GH, he in order, we must get parallelogram; () B: connect EQ, QG in order (2) please choose one of a and B to prove your judgment. (3) if the quadrilateral ABCD is shown in Figure 2, please judge whether the two conclusions in (1) are true or not?

(1) (2) prove: (1) the judgment of a in: (1) connect EF, FG, GH and he. ∵ E and F are the midpoint of AB and BC respectively, ∵ EF ∥ AC, EF = 12ac. Similarly, get Hg ∥ AC, Hg = 12ac, ∥ EF ∥ Hg, EF = Hg, ∥ quadrilateral efgh is a parallelogram. (3) similar to the conclusion in (1) (both a and B hold) and proof

As shown in the figure, in the parallelogram ABCD, the diagonal lines AC and BD intersect o, EO ⊥ AC. (1) if the perimeter of △ Abe is 10cm, find the perimeter of the parallelogram ABCD; (2) if ∠ ABC = 78 ° AE bisection ∠ BAC, try to find the degree of ∠ DAC

(1) The circumference of △ Abe is ab + AC = 10. According to the equality of the opposite sides of the parallelogram, ▱ ABCD is 2 × 10 = 20cm. (2) ∵ AE = CE, ∵ EAC = ∠ ECA, ∵ ABC = 78 °, AE bisection ∠ BAC, ∵ BAE = ∠ EAC = 39 °, ∥ ad ∥ BC, ∵ DAC = ∠ EAC = ∠ ECA = 39 °

The quadrilateral ABCD is a parallelogram, O is the intersection point of diagonal, EF passes through O and intersects with AD and BC at E.F. this paper describes how △ AOE is rotated
coincidence
When ×× rotates ×× angle around ×× direction, we get ×× as the basic angle

A quadrilateral ABCD is a parallelogram
∴OA=OC,OB=OD,∠AOE=∠COF,∠EAO=∠FCO
∴△AOE≌△COF
Therefore, △ AOE can be rotated 180 ° clockwise around point O to coincide with △ COF

As shown in the figure, the quadrilateral ABCD is a parallelogram. The diagonal lines AC and BD intersect at point O. draw a straight line EF passing through point O and intersect AD and BC at points E and f respectively. Verify that OE = of

Certification:
A quadrilateral ABCD is a parallelogram,
∴AD∥BC,AO=CO,
∴∠EAO=∠FCO,
∵∠AOE=∠COF,
∴△AOE≌△COF,
∴OE=OF.

In the following conditions, the one that can judge whether the quadrilateral ABCD is a parallelogram is ()
A. AB∥CD，AD=BCB. AB=AD，CB=CDC. AB=CD，AD=BCD. ∠B=∠C，∠A=∠D

A. According to ad ∥ CD, ad = BC can't judge quadrilateral ABCD is parallelogram, so this option is wrong; B. according to ab = ad, BC = CD, can't judge quadrilateral ABCD is parallelogram, so this option is wrong; C. according to ab = CD, ad = BC, it is concluded quadrilateral ABCD is parallelogram, so this option is correct; D. according to ∠ B = ∠ C, ∠ a = ∠ D, can't judge quadrilateral ABCD is parallelogram , so this option is wrong; so select C

As shown in the figure, P, Q and R are respectively the midpoint of edges AC, BC and BD of a-bcd, and the plane intersection ad passing through three points P, Q and R is at s

It is proved that ∵ P is the midpoint of AC, q is the midpoint of BC, ∵ PQ ∥ AB, and PQ = 12ab (1 point) ∵ PQ ⊂ plane PQRS, ab ⊄ plane PQRS, ∥ ab ⊉ plane PQRS (3 points) ∩ plane PQRS ∩ plane abd = RS, ab ⊂ plane abd, ∩ ab ∥ rs (5 points) ∵ R is the mid point of BD, s is the mid point of AD (6 points) ∥ RS ∥ AB, and rs = 12ab. ∥ RS ∥ PQ, and rs = PQ. ∥ PQRS is a parallelogram (8 points)

In known parallelogram ABCD, ab = 20cm, ad = 16cm, the distance between AB and CD is 8cm, find the distance between AD and BC

Let the distance between AD and BC be x cm
AB*8=AD*X
X=10

As shown in the figure, the circumference of the circle is 25.12 cm, and the area of the circle is exactly equal to that of the rectangle. How long is the rectangle?