The ratio of the length of the two arcs divided by the chord is 2:7, and the degree of the circumferential angle of the chord is______ .

∵ string AB divides ⊙ o into two parts of 2:7,
Qi
AMB=360°×7
9=280°，
∴∠AOB=280°，
∴∠AMB=1
2∠AOB=1
2×280°=140°，∠ANB=180°-∠AMB=180°-140°=40°．
So the answer is: 40 ° or 140 °

If a chord of a circle divides the circle into two arcs with a degree ratio of 1:3, the angle of the circle to which the chord is opposite is equal to () A. 45° B. 135° C. 90 ° and 270 D. 45 ° and 135 ° respectively

As shown in the figure, the chord AB divides ⊙ o into two arcs with degree ratio of 1:3
When OA and ob are connected, AOB = 90 °;
① When the vertex of the circle angle is located at point D,
The circular angle of the chord is ∠ ADB = 1
2∠AOB=45°；
② When the vertex of the circle angle is located at point C,
The circular angle of the chord is ∠ ACB = 180 ° - ∠ ADB = 135 °
Therefore, D

If the chord center distance is 4 and the chord length is 8, the inferior arc length is () A. 2 pi B. 4π C. 2 2 pi D. 8π

As shown in the figure, connect OA and ob,
∵ OC ⊥ AB, OC over O, ab = 8,
∴AC=BC=4，
∵OC=4，
∴AC=BC=OC，
∴∠AOB=90°，
In RT △ ACO, the result of Pythagorean theorem is: OA=
42+42=4
2，
The length of inferior arc AB is 90 π × 4
Two
180=2
2π，
Therefore, C

If a chord of a circle is 6cm long and its chord center distance is equal to 4cm, then the radius of the circle is equal to______ cm．

Ad = 1 is obtained from the vertical diameter theorem
2AB=6÷2=3cm，
In the right angle △ oad, the radius OA can be obtained according to Pythagorean theorem=
32+42=5cm．

If the radius of circle O is 2cm and the minor arc of chord AB is one third of the circle, then the length of chord AB is and the chord center distance of AB is

The center angle of the circle to which ab is directed is 120 degrees,
AB/2=BD=OBsin60°=√3
AB＝2√3（cm)
The chord center distance of AB = od = obcos60 ° = 1 (CM)

Given that the radius of circle O is 2cm, the minor arc of chord AB is one third of the circumference of circle. Find the length of chord AB and chord center distance! The circle should be drawn by itself

The minor arc of string AB is one third of the circumference of the circle
The center angle is 120 degrees
Chord center distance = 1
AB = 2 roots 3

If the distance between the chord centers of a string is equal to 1 / 4 of the diameter of the circle it is in, what is the degree of the arc the string is facing

If the center distance of a circle = half of the radius, then: [chord is ab, midpoint of AB is p, center of circle is C]
In a right triangle ACP, the right angle side CP is equal to half of the hypotenuse Ca, then:
If the angle ACP = 60 °, the angle AOB of the center of the circle is 120 °
The degree of the arc to which string AB is directed is 120 degrees

If the sum of a chord and chord center distance in a circle is equal to the diameter, and the chord center distance is 1, then the diameter of the circle is A:1 B:1.5 C:2 D:2.5 Come on

D. Let the radius of the circle be r. then the chord length is 2r-1. According to Pythagorean theorem, 1 ^ 2 + [(2r-1) / 2] ^ 2 = R ^ 2 is obtained, and the solution is r = 2.5

In circle O, if the distance between the chord centers of a string is equal to half of the radius of the circle, how many degrees is the center angle of the string to

One hundred and twenty

The radius of a circle is not only the ratio median of two chords, but also the difference between the two chords

The radius of a circle is not only the proportional median of two chords, but also the difference between the two chords. If the lengths of these two chords are a and B respectively, and a > b, then AB = R? And A-B = R are obtained. The solution is a = (1 + √ 5) R / 2, B = (- 1 + √ 5) R / 2, that is, a / (2R) = (1 + √ 5) / 4, B / (2R) = (- 1 + √ 5) / 4 because sin18 ° = (- 1 + √ 5) / 4, sin54 ° = cos36

The ratio of the length of the two arcs divided by the chord is 2:7, and the degree of the circumferential angle of the chord is______ .