If there is a chord of length r in the circle with radius r, what is the degree of circumference angle corresponding to the chord

The end line of the center and chord is a regular triangle, the center angle = 60 ° and the circumference angle = 30 °

If there is a chord of length r in the circle with radius r, the degree of the circle angle to which the chord is opposite is () A. 30° B. 30 ° or 150 ' C. 60° D. 60 ° or 120 '

∵ chord with radius R and length R,
The chord and two radii form an equilateral triangle,
The center angle of the circle to which the string is aligned is 60 °,
① When the vertex of the circumference angle is on the superior arc, the circumference angle is equal to 30 °;
② When the vertex of the circumference angle is on the inferior arc, the circumference angle is equal to 150 degrees
Therefore, B

The radius of circle O is known to be 1, chord AB = radical 3, chord AC = radical 2. Find the degree of the circumference angle of the circle ∠ BAC

Two right triangles can be obtained by connecting the other end point of the diameter and the other intersection point of the chord. Because AB = radical 2, one angle is 45 degrees. AC = radical 3, the other angle is 30 degrees. If these two chords are on the same side of the diameter, the angle bac = 45-30 = 15 ° if the opposite side is: angle BAC = 45 + 30 = 75 °

The radius of the circle is 9, and the circumference angle of the chord pair with length of 9 =? The circumference angle of the chord pair with the length of 9 × 2 =? The circumference angle of the chord pair with the length of 9 × 3 =?

Connect the center of the circle, the midpoint of the chord, and the radius to form a right triangle
Let a chord of length 9 be a, then sin (A / 2) = (9 / 2) / 9 = 1 / 2
Therefore, if a / 2 = 30, that is, the center angle of the circle is 60 degrees, then the circumference angle = 60 / 2 = 30 degrees
2. If the angle of a chord whose length is 9 Radix 2 is B, then sin (B / 2) = (9 radical 2 / 2) / 9 = radical 2 / 2
Therefore, B / 2 = 45, that is, the center angle of the circle is 90 degrees, then the circumference angle is 45 degrees
3. If the angle of a chord with a length of 9 root sign 3 is x, then sin (x / 2) = (9 root 3 / 2) / 9 = root 3 / 2
So the angle of the circle is 60 degrees

In a circle with a radius of 5cm, there is a length of 5 For a chord of 3cm, the circular angle of the chord is () A. 120° B. 30 ° or 120 ' C. 60° D. 60 ° or 120 '

According to the meaning of the title, draw the corresponding figure as follows: connect OA, ob, take a point E on the superior arc AB, connect AE, be, take a point F on any minor arc AB, connect AF, BF, and make OD ⊥ AB through O, then D is the midpoint of AB, ∵ AB = 53cm,

In a circle with a radius of 5cm, there is a chord with a length of 5 √ 2cm. Find the degree of the circular angle to which the chord is aligned

45 ° and 135 ° respectively
Make the vertical line of the string through the center of the circle. Connect one end of the line to the center of the circle
If the radius is 5 and the center distance is (5 / 2) √ 2, it is an equal right triangle
The degree of the angle of the center of the circle to which the chord is opposite is 90 degrees
The degree of the circumferential angle to which the chord is to be 45 ° and 135 ° respectively

As shown in the figure, the radius of ⊙ o is 1, AB is a chord of ⊙ o, and ab is a chord of ⊙ o= 3, then the degree of the circumference angle of the chord AB is______ .

As shown in the figure, connect OA and ob, and make of ⊥ AB through O, then AF = 12ab, ∵ AOF = 12 ∵ AOB, ? OA = 1, ab = 3, ? AF = 12ab = 12 × 3 = 32, ? sin  AOF = afoa = 321 = 32,  AOF = 60 °, ? AOF = 2 ﹤ AOF = 120 °, ? AOF = 12 ﹤ AOB = 12 × 120 ° = 60

As shown in the figure, the radius of circle O is 1, chord AB = radical 3, and the degree of the circumference angle ∠ ACB is calculated

Drawing a 120 ° drawing, the chord is one side of the triangle, and the radius is the other two sides of the triangle. Through the center O, make a vertical line to the chord AB, and the foot of the perpendicular is e. according to the isosceles triangle, the three lines are in one, so e is the midpoint of AB, so EB is the root of two thirds, radius ob is 1

In ⊙ o with radius 1, if chord AB = 1, then The length of AB is () A. π Six B. π Four C. π Three D. π Two

As shown in the figure, make OC ⊥ ab,
According to the vertical diameter theorem, BC = 1
Two
∵ chord AB = 1,
∴sin∠COB=1
Two
∴∠COB=30°
∴∠AOB=60°
Qi
Length of AB = 60 π
180=π
3．
Therefore, C

In the circle O with radius 2, the chord AB is equal to 2 radicals. 3. Find the length of arc AB?

4pai in 3

If there is a chord of length r in the circle with radius r, what is the degree of circumference angle corresponding to the chord