Circle Properties, Angles, and Equations

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Questions and Answers

Write an equation of a circle with a center at $(-7, 1)$ and radius $r = 7$.

$(x+7)^2 + (y-1)^2 = 49$

Name three points that lie on the circle defined by the equation $(x+7)^2 + (y-1)^2 = 49$.

Examples: $(-7, 8)$, $(0, 1)$, $(-14, 1)$, $(-7, -6)$. (Any point satisfying the equation is correct).

Given Circle C with diameter RU, find the measure of arc ST (mST).

$75^\circ$

Given Circle C with diameter RU, find the measure of arc QUS (mQUS).

<p>$270^\circ$</p> Signup and view all the answers

Find the value of x in the diagram where two chords intersect inside the circle.

<p>$68^\circ$</p> Signup and view all the answers

Given Circle C, find the value of x.

<p>$47^\circ$</p> Signup and view all the answers

Given Circle C, find the value of y.

<p>$133^\circ$</p> Signup and view all the answers

Find the value of x in the diagram where an angle is formed by two secants intersecting outside the circle.

<p>$50^\circ$</p> Signup and view all the answers

Given: AE = 8, AH = 7, ES = y, and HL = y + 3. Find the value of y using the intersecting secants theorem.

<p>6</p> Signup and view all the answers

In Circle G, $mArc(KV) = (7x)^\circ$, $mArc(SK) = (5x + 55)^\circ$, $mArc(VS) = 65^\circ$. Find the measure of arc SK (mSK).

<p>$155^\circ$</p> Signup and view all the answers

Given the $mArc(CJM) = (5x + 20)^\circ$ and $m\angle CMN = 115^\circ$, find the value of x.

<p>42</p> Signup and view all the answers

Using the diagram where two secants intersect outside the circle, find the value of x.

<p>5</p> Signup and view all the answers

Write the equation of a circle with diameter endpoints A(3,0) and B(7,6).

<p>$(x-5)^2 + (y-3)^2 = 13$</p> Signup and view all the answers

In diagram 9a, find the value of x, representing the measure of arc AB assuming central angle AOB=96.

<p>$96^\circ$</p> Signup and view all the answers

In diagram 9a, find the value of z, representing an angle in the isosceles triangle OAE, assuming arc AE is $96^\circ$.

<p>$42^\circ$</p> Signup and view all the answers

Using the calculation $x = (96-24)/2$ based on diagram 9b where 96 and 24 represent intercepted arcs, find the value of x.

<p>$36^\circ$</p> Signup and view all the answers

Using the calculation $y = (96+24)/2$ based on diagram 9b where 96 and 24 represent intercepted arcs, find the value of y.

<p>$60^\circ$</p> Signup and view all the answers

Using the calculation $z = 96/2$ based on diagram 9b where 96 represents an intercepted arc, find the value of z.

<p>$48^\circ$</p> Signup and view all the answers

What is the perimeter of $ riangle ABC$, given that segments AB, BC, and CA are tangent to Circle O?

<p>20 units</p> Signup and view all the answers

Given $OB = \sqrt{28}$, what is the radius of Circle O?

<p>$\sqrt{3}$ units</p> Signup and view all the answers

What is the value of x (the central angle) in the diagram for question 10?

<p>$120^\circ$</p> Signup and view all the answers

Given Circle C with radius 6 and $m\angle ACB = 100^\circ$, find the length of arc AB. Simplify your answer and leave it in terms of $\pi$.

<p>$\frac{10}{3}\pi$ units</p> Signup and view all the answers

In a circle whose radius is 6 in., the area of a sector is $15\pi$ in$^2$. Find the measure of the central angle of the sector.

<p>$150^\circ$</p> Signup and view all the answers

Find the area of the shaded region, assuming it is a circular segment defined by a $90^\circ$ central angle in a circle with radius 8 cm (based on calculation notes).

<p>$16\pi - 32$ square units (approx 18.3 square units)</p> Signup and view all the answers

In diagram 14, find the value of angle a.

<p>$90^\circ$</p> Signup and view all the answers

In diagram 14, find the value of angle b.

<p>$90^\circ$</p> Signup and view all the answers

In diagram 14, find the value of angle c.

<p>$70^\circ$</p> Signup and view all the answers

In diagram 14, find the value of angle d.

<p>$65^\circ$</p> Signup and view all the answers

In diagram 15, where l1 and l2 are tangents, find the value of angle b.

<p>$90^\circ$</p> Signup and view all the answers

In diagram 15, find the value of angle c.

<p>$42^\circ$</p> Signup and view all the answers

In diagram 15, find the value of angle d.

<p>$70^\circ$</p> Signup and view all the answers

In diagram 15, find the value of angle e.

<p>$48^\circ$</p> Signup and view all the answers

In diagram 15, find the value of angle f.

<p>$132^\circ$</p> Signup and view all the answers

In diagram 15, find the value of angle g.

<p>$50^\circ$</p> Signup and view all the answers

Solve for x using the intersecting secants theorem and the quadratic formula, based on the diagram in question 16.

<p>2</p> Signup and view all the answers

Solve for x using the tangent-secant theorem based on the diagram in question 18.

<p>6 units</p> Signup and view all the answers

Flashcards

Inscribed Angle

An angle whose vertex is on the circle and whose sides are chords of the circle.

Semicircle

Half of a circle, an arc whose measure is 180 degrees.

Tangent

A line that touches a circle at only one point.

Secant

A line that intersects a circle at two points.

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Chord

A line segment connecting two points on a circle.

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Minor Arc

An arc of a circle that is less than 180 degrees.

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Major Arc

An arc of a circle that is greater than 180 degrees.

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Diameter

A straight line passing through the center of a circle, connecting two points on the circumference.

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Intercepted Arc

The arc formed where an angle 'cuts' the circle.

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Central Angle

An angle whose vertex is at the center of the circle.

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(x-h)^2+ (y-k)^2=r^2

Equation of a circle in standard form.

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Study Notes

Circle Parts

  • ∠FDB is an inscribed angle.
  • DFB is a semicircle.
  • AH is a tangent.
  • CG is a secant.
  • DF is a chord.
  • EG is a minor arc.
  • FEG is a major arc.
  • DB is a diameter.
  • FB is an intercepted arc.
  • ∠JPB is a central angle.

Equation of a Circle

  • The equation of a circle with a center at (-7, 1) and a radius of 7 is (x+7)² + (y-1)² = 49.

Circle Measurements

  • Given circle C with diameter RU, if m arc ST = 75°, then m arc QUS = 270°.
  • x = 68
  • In circle O, if arc y = 133° then x = 47 and y = 133°.
  • x = 50
  • If AE = 8, AH = 7, ES = y, and HL = y + 3, then y = 6.

Arcs and Angles in a Circle

  • In circle G, if m arc KV = (7x)°, m arc SK = (5x + 55)°, and m arc VS = 65°, then x = 20 and m arc SK = 155°.
  • Given m arc CJM = (5x + 20)° and m∠CMN = 115°, then x = 42.
  • (2x-1) (4) = (x-2)(x+7), x = 5

Equation of a Circle with Given Diameter

  • For a circle with diameter AB where A(3,0) and B(7,6), the center is (5,3).
  • The equation of the circle is (x-5)² + (y-3)² = 13.

Circle Angles

  • If FA and ET are not diameters of circle O, then x = 96°, y = 96°, and z = 42°.
  • Given x = 36, y = 60 and z = 48

Tangent and Perimeter Calculations

  • If AB, BC, and CA are tangent to circle O, the perimeter of triangle ABC is 20 units.
  • If OB = √28 = 2√7, the radius is √3.
  • The value of x in the quadrilateral is 120°.
  • The length of arc AB in circle C is (10/3)Ï€ units when the measure of arc AB is 100° and the radius is 6.

Area of a Sector

  • Given radius is 6, the measure of the central angle of the sector is 150° when the area of the sector is 15Ï€.

Area of Shaded Region

  • The area of the shaded region is approximately 18.3 units².

Circle Variables

  • a = 90°
  • b = 90°
  • c = 70°
  • d = 65°
  • b = 90°
  • d = 70°
  • e = 48°
  • f = 132°
  • c = 42°
  • g = 50°

Solving for Variables

  • 3x(3x+4x) = (3x+1)(3x+1+2x+1), x = 2
  • AC and DB are diameters of circle J, AE ≅ CE ≅ DE ≅ EB, ∠AED ≅ ∠BEC. Hence, triangles ΔEAD ≅ ΔECB by SAS.
  • Tangent = secant, x = 6 units

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