What is the sector area formula? The one with arc degrees

What is the sector area formula? The one with arc degrees

If the radian number of the circle center angle of the sector is a and the radius of the circle where the sector is located is r, then the area s = (1 / 2) ar ²

If the circumference of the sector is 8cm and the area is 4cn ^ 2, then the radian number of the circle center angle of the sector is the answer process and operation formula,

It doesn't matter if the unit is wrong. Count it first
Let radians be α, Radius r
Sector perimeter: α* r+2r=8 ①
Sector area: α/ 2π*（π*r ²）= 4 so α* r ²= 8 ②
By ① α= (8-2r) / R is substituted into ② to get (8-2r) * r = 8, that is, R ²- 4r+4=0
So r = 2
Substitute ① α= two
The number of radians is 2

Change 2.718. From radian to angle

2.718=2.718x180°/π

Both radian and angle are converted What is 90 degrees to radians

π = 180 degrees
So, 90 degrees = π / 2
Those who don't understand are welcome to ask,

How to use formulas or functions in Excel to convert degrees into radians, such as 213 degrees, 14 minutes and 33 seconds, find its cosine value, and give the expression of the formula Know the azimuth in Excel, and the angle is expressed in degrees. They are all angles with degrees, minutes and seconds, such as 213 degrees, 14 minutes and 33 seconds. How to find its sine and cosine values, and give the expression of the formula or the expression of the function Know the azimuth in Excel, and the angle is expressed in degrees, all of which are degrees, minutes and seconds, such as 213 degrees, 14 minutes and 33 seconds. How to find its sine and cosine values, and give the expression of the formula or function. You can give a general formula or express it with the function radins () in Excel,

=Cos (60 * PI () / 180) 60 degree
=Cos (12.5 * PI () / 180) 12.5 degrees
=Sin (75 * PI () / 180) 75 degrees
213 degrees, 14 minutes and 33 seconds = 213 + 14 / 60 + 33 / 3600 =... Substitute into the above formula
Here's an article for you

Conversion formulas for the degree, time and watt of domestic electricity Given the wattage (rated power) and power consumption time of the electrical appliance, find out how many kilowatts are used In addition, the degree of electricity used is not the real degree in ordinary life? If there is an error, where does the error come from?

Power consumption = electrical watt (unit: kW) * power consumption time (hour)
For example, the power consumption of an induction cooker with a rated power of 1 kW for one hour is 1 kwh, i.e. 1 degree
It is usually the true degree
If there is any error, it is mainly caused by voltage instability