The rectangle is 80 meters long and 60 meters wide. Now the length and width are increased by 20 meters. How many square meters is the current area

The rectangle is 80 meters long and 60 meters wide. Now the length and width are increased by 20 meters. How many square meters is the current area

S=(80+20)*(60+20)=8000

How many millimeter cameras do you use for 10 meters wide and 50 meters long?
People who can see their heads

How many mm lens you need depends on your actual location
Generally, the number of millimeters is 3.6mm, 6mm, 8mm, 12mm, 16mm. These are the most commonly used angles that are inversely proportional to the distance. The larger the angle, the closer the distance is. The 3.6mm lens is 67.4 degrees away from 15m, the 6mm lens is 42.3 degrees away from 20m, the 8mm lens is 32.6 degrees away from 25m, the 12mm lens is 22.1 degrees away from 40m, the 16mm lens is 17.1 degrees away from 60m
In order to obtain the expected camera effect, we should pay attention to six basic elements when selecting the lens
A) the size of the subject
B) detail size of the subject
C) object distance
D) focal length
E) target size of CCD camera
F) resolution of lens and camera system
Focal length calculation: formula calculation method: field of view and focal length calculation. The field of view refers to the size of the object to be taken in. The size of the field of view is determined by the distance from the lens to the object to be taken in, the focal head of the lens and the required imaging size. 1. The focal length of the lens, the size of the field of view and the distance from the lens to the object to be taken in are calculated as follows: F = WL / W2, f = HL / h
F; lens focal length
W: the width of the image (the imaging width of the object on the CCD target)
W: subject width
L: distance from the subject to the lens
H: image height (imaging height of the object on the CCD target) field of view (scene) height
H: the height of the subject
CCD target size: mm
Specification 1 / 3 "1 / 2" 2 / 3 "1"
　　W 4.8 6.4 8.8 12.7
　　H 3.6 4.8 6.6 9.6
Focal length specification angle
2.1 mm small lens 1 / 3 150 degree
2.5mm small lens 1 / 3 130 degree
2.8mm small lens 1 / 3 115 degree
2.8mm fixed aperture 1 / 3 115 degree
　　2.8mm 1/3 96°
　　4mm 1/3 78°
　　6mm 1/3 53°
　　8mm 1/3 40°
　　12 mm 1/3 23°
　　16 mm 1/3 17°
　　3.5-8mm 1/3 96°- 45°
　　6-15mm 1/3 54°- 23°
6-36mm electric zoom lens 1 / 3 51 ° - 9 °
8.5-51mm electric zoom lens 1 / 3 57 ° - 10 °
Zoom 3-60mm-6-6

50 square meters of ground, 10 meters long, 5 meters wide, 0. 20 meters thick, concrete, how many materials

According to the mass ratio of 1:2:3 (cement; yellow sand; gravel), the concrete with thickness of 0.20 m generally uses about 1.5 bags of cement (50kg per bag) per square meter