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How to calculate the circumference and area of a circle
2 π r perimeter π R. r r is the radius
How to find the area of the circumference of a circle
If the circumference is 25.12, give the following formula
I'm glad to be able to answer your question here
Find the radius first
(25.12/3.14)/2=8/2=4
So the area is
3.14*4*4=50.24
Perimeter = 3.14 * diameter
Area = 3.14 * diameter * diameter / 4
So, if you know the perimeter, then
Area = perimeter * perimeter / (3.14 * 4)
AB is the diameter of circle O, EF is the chord of circle O, ad is perpendicular to EF, BC is perpendicular to EF, and the perpendicular feet are D and C respectively
Those who answer this question will be blessed forever
Because ad is perpendicular to EF, BC is perpendicular to ef
Angle ADO = angle BCO = 90 degrees
AB is the diameter
AO=BO
Triangle ADO is equal to triangle BCO (HL)
DE=CF
The diameter of circle O AB = 4, the chord AC and ab form 45 degrees, find the distance from the center O to AC
Oh, cry
Connecting BC, we get the angle c = 90. (because AB is the diameter)
If the angle BAC is 45, the triangle ABC is an isosceles right triangle
AB = 4, AC = BC = 2, radical 2
Connecting OC, the triangle ACO is also isosceles right triangle
CO is perpendicular to ab
Then the distance from O to AC = AC / 2 = root 2
In ⊙ o, AB is the diameter, AC is the chord, the distance between points B and C is 2cm, then the distance from the center of the circle to the chord AC is______ cm．
As shown in the figure, ∵ AB is the diameter, ∵ C = 90 °, ∵ OD ⊥ AC, ∵ OD ∥ BC, ∵ od = 12bc, ∵ BC = 2cm, ∵ od = 1cm, the distance from the center of circle to the chord AC is 1cm, so the answer is 1
AB is the diameter of the circle, C is a point on the circle, PC is perpendicular to the plane of the circle, if BC = 1, AC = 2, PC = 1, then the distance from P to AB is?
3 / 5 root 5
Let ch be the vertical line of AB through C, and let pH be the vertical line of ab
Because ch ⊥ AB, PC ⊥ AB, then pH ⊥ ab
In RT Δ ABC, the root 5 with CH 2 / 5 can be obtained
In RT Δ PCH, the root number of pH5 is 3 / 5
The length of pH is obtained
If AB = 5cm, BC = 3cm, and a, B, C are on the same line, then the distance between a and C is______ ．
When point C is between AB, AC = ab-bc = 5-3 = 2cm; when point C is on the right side of point B, AC = AB + BC = 5 + 3 = 8cm
If AB = 5cm, BC = 3cm, then the distance between a and C is?
It doesn't say ABC is in a straight line
If C is between AB, then the distance between a and C is 2 cm;
If C is outside AB, the distance between a and C is 7 cm;
If AB and BC are parallel, then the distance between a and C will never intersect
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