As shown in the figure, in the triangle ABC, D, e and F are the midpoint of three sides BC, AC and ab respectively. It is proved that the quadrilateral defb is a parallelogram

As shown in the figure, in the triangle ABC, D, e and F are the midpoint of three sides BC, AC and ab respectively. It is proved that the quadrilateral defb is a parallelogram

∵ D E is the midpoint of BC, AC and ab respectively
The De is the median of △ ABC
BF=1/2 BC
The De is parallel to BC and equal to 1 / 2 BC
The quadrilateral defb is a parallelogram [a set of opposite sides are parallel and equal]

As shown in the figure, in △ ABC, D, e and F are the midpoint of edges AB, BC and Ca respectively. It is proved that the quadrilateral decf is a parallelogram

It is proved that: ∵ D and F are the middle points of edges AB and Ca respectively. ∵ DF ∥ BC, DF = 12bc = EC, ∵ quadrilateral decf is a parallelogram

As shown in the figure, in △ ABC, D, e and F are the midpoint of edges AB, BC and Ca respectively. It is proved that the quadrilateral decf is a parallelogram

It is proved that: ∵ D and F are the middle points of edges AB and Ca respectively. ∵ DF ∥ BC, DF = 12bc = EC, ∵ quadrilateral decf is a parallelogram

The diameter of a semicircle iron plate is 20 cm, its perimeter is (), and its area is (). The diameter of a small circle is 5 cm, the radius of a large circle is 5 cm, and the surface of a small circle is 5 cm
A semicircular iron plate with a diameter of 20 cm has a circumference of () and an area of ()
The diameter of the small circle is 5cm, the radius of the big circle is 5cm, and the area of the small circle is ()% of the area of the big circle

A semicircular iron plate, 20 cm in diameter, has a circumference of (10 π + 20) cm and an area of (50 π) square cm
The diameter of the small circle is 5cm, the radius of the large circle is 5cm, and the area of the small circle is (25)%
100% correct

Answer the circumference and area of a circle: a rectangular iron plate is 20 decimeters long and 8 decimeters wide. Cut off the two largest round iron plates from the rectangular iron plate
What's the area of the building

8 / 2 = 4 S = 2 π r = 2 * 3.14 * 4 = 25.12 (square decimeter) 25.12 * 2 = 50.24 (square decimeter)

In a rectangle 12dm in length and 4dm less in width than in length, cut the largest square whose perimeter is______ The area is______ And the rest is one______ What's its circumference______ The area is______ ．

(1) 12-4 = 8 (decimeter), perimeter of square: 8 × 4 = 32 (decimeter), area of square: 8 × 8 = 64 (square decimeter), (2) length of remaining rectangle is 12-8 = 4 (decimeter), width is 8 decimeter, so perimeter is: (8 + 4) × 2 = 24 (decimeter), area is: 8 × 4 = 32 (square decimeter), so the answer is: 32 decimeter; 64 square decimeter; 24 decimeter; 32 square decimeter Rice

A batch of round iron plates are processed. It is known that the perimeter of each iron plate is 12.56 meters. What is the area of each iron plate in square meters?

3.14 × (12.56 ﹣ 3.14 ﹣ 2) & ﹣ 178; = 12.56 square meters

A batch of round iron plates are processed. It is known that the perimeter of each iron plate is 12.56 meters. What is the area of each iron plate?

12.56 ﹣ 3.14 ﹣ 2 = 2 (m) radius
3.14 * 4 & # 178; = 12.56 (M2) the measure of area

The surface area of the cuboid is 1.6 square meters, and the bottom is a square with a circumference of 1.6 meters. How many cubic decimeters is the volume of the cuboid

1.6 △ 4 = 0.4m
(1.6-0.4 × 0.4 × 2) △ 4 △ 0.4 = 0.8m
0.4 × 0.4 × 0.8 = 0.128 cubic meters = 128 cubic decimeters

The shape of an iron plate is shown in the figure. Paint the two sides of the iron plate. What is the area of the paint? (unit: decimeter)

8 × 8 + (4 + 2 + 4 + 2) × (10-8) △ 2 = 64 + 12 × 2 △ 2 = 64 + 12 = 76 (square decimeter) 76 × 2 = 152 (square decimeter) a: the area of painting is 152 square decimeter