Draw a circle on a 1:400 scale drawing. The actual area of the circle is known to be 80 square meters, and the area on the drawing of the circle is () square centimeters

Draw a circle on a 1:400 scale drawing. The actual area of the circle is known to be 80 square meters, and the area on the drawing of the circle is () square centimeters

80/400^2*10000=5cm^2

A square playground with an area of 2500 square meters is drawn on the drawing with an area of 16 square centimeters. What's the scale of this drawing?
Find out the side length with X

50 * 50 = 2500 square meters
The actual side length is 50m = 5000cm;
4 * 4 = 16 square centimeters
The side length of the picture is 4cm
4: 5000 = 1:1250 (scale)

A vegetable field is enclosed by a wall (as shown in the picture). The fence is 48 meters long. How many square meters is the area of this vegetable field?

Use a 58 meter long fence to enclose a vegetable field 10 meters wide near the wall. How many square meters is the area of this field?
Use a 58 meter long fence to surround a vegetable field near the wall (as shown in the picture). What is the area of this land in square meters?

Width: 10M, length: 58 - (2 * 10) = 38m
So area = 10 * 38 = 380 square meters

A vegetable field is enclosed by a wall (as shown in the picture). The fence is 48 meters long. How many square meters is the area of this vegetable field?

Granny Wang's family has a square vegetable plot (as shown in the picture). One side of the plot is against the wall and surrounded by a fence. The fence is 48 meters long

Side length: 48 △ 3 = 16M
Area: 16 × 16 = 256 square meters

Give examples of applying Archimedes principle in production or life?

1. Bamboo chops
2. Aircraft carrier
3. Submarine
4. Balloons and airships
5. Densitometer
6. Skillfully measuring the density of human blood by buoyancy
7. Salt water seed selection

"A different way of thinking, a different angle" gives examples in life
Just one,

Two people went to sell shoes. They also went to a place where people never wear shoes. One thought: it's over. People here don't wear shoes, so my shoes can't be sold. The other thought: great, people here don't wear shoes, so my shoes can be sold

Using symmetry, translation, rotation to design patterns, changed the () and () of the basic graphics, did not change the () of the basic graphics
Using symmetry, translation, rotation to design patterns, changed the () and () of the basic graphics, did not change the () and () of the basic graphics

Position, direction, shape and size (the first two are not very certain)

Solution: when measuring, the correction coordinate is wrong. How to translate and rotate the figure to the correct position has been measured
I first expand the common points of correct measurement into CASS, then insert the error diagram into CASS, and then translate, but the translation does not move

What instrument do you use to measure what workpiece