Geometry: Area of Semicircles and Sectors
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Questions and Answers

How is the area of a semicircle found?

Take half the area of the whole circle.

Find the length of an arc of 40° in a circle with an 8 inch radius.

16 π/9 inches

What is the radius of a circle in which a 30° arc is 2 π inches long?

12 inches

What is the degree measure of an arc 4 π ft long in a circle of radius 10 ft?

<p>72°</p> Signup and view all the answers

A bicycle wheel with radius 26" rotates through an arc that measures 80°. What is the length of the arc of the tire that touched the ground?

<p>11.56 π inches</p> Signup and view all the answers

If the length of an arc is 12 π inches and the radius of the circle is 10 inches, what is the measure of the arc?

<p>216 degrees</p> Signup and view all the answers

What part of the circumference is an arc whose measure is 30°?

<p>1/12</p> Signup and view all the answers

What is the area of a sector with radius 10" and measure of arc equal to 45°?

<p>12.5 π sq.inches</p> Signup and view all the answers

What is the area of a sector with measure of arc equal to 90° and radius equal to 1 foot?

<p>0.25 π sq.inches</p> Signup and view all the answers

What is the area of a sector with radius equal to 8 and measure of arc equal to 300°?

<p>53.3 π</p> Signup and view all the answers

In a circle of radius 10 cm, a sector has an area of 40 π sq.centimeters. What is the degree measure of the arc of the sector?

<p>144°</p> Signup and view all the answers

What is the radius of a circle with a sector area of 7 π sq.ft and an arc whose measure is 70°?

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

A 10" diameter pumpkin pie is cut into six equal servings. What is the area of the top of each piece of pie?

<p>4.17 π square inches</p> Signup and view all the answers

An equilateral triangle with a side of 2√3 is inscribed in a circle. What is the area of one of the sectors formed by the radii to the vertices of the triangle?

<p>1.33 π square inches</p> Signup and view all the answers

A square with sides of 3√2 is inscribed in a circle. What is the area of one of the sectors formed by the radii to the vertices of the square?

<p>2.25 π</p> Signup and view all the answers

Study Notes

Area of Semicircles and Sectors

  • The area of a semicircle is calculated as half the area of a full circle.

Arc Length Calculations

  • For a circle with an 8-inch radius, the length of a 40° arc is 16 π/9 inches.
  • In a circle where a 30° arc is measured as 2 π inches long, the radius is determined to be 12 inches.
  • An arc measuring 4 π ft in a circle with a radius of 10 ft corresponds to a degree measure of 72°.
  • A bicycle wheel with a radius of 26 inches rotates through an 80° arc, resulting in an arc length of 11.56 π inches.

Arc Measure Derivations

  • Given an arc length of 12 π inches and a circle radius of 10 inches, the degree measure of the arc is found to be 216 degrees.
  • An arc measuring 30° accounts for 1/12 of the total circumference of the circle.

Area of Sectors

  • The area of a sector with a radius of 10 inches and an arc measure of 45° is 12.5 π square inches.
  • For a sector with a 90° arc and a radius of 1 foot, the area is calculated as 0.25 π square inches.
  • A sector with a radius of 8 and an arc measure of 300° has an area of 53.3 π square inches.

Sector Area and Arc Measures

  • In a circle where the radius is 10 cm, a sector area of 40 π square centimeters corresponds to a degree measure of 144°.
  • A sector area of 7 π square feet with an arc measure of 70° indicates a radius of 6 feet.

Practical Applications

  • For a 10" diameter pumpkin pie cut into six equal servings, the area of each piece is approximately 4.17 π square inches.
  • An equilateral triangle inscribed in a circle with sides of 2√3 yields a sector area of 1.33 π square inches for one of its sectors.
  • A square inscribed in a circle with sides of 3√2 results in a sector area of 2.25 π square inches.

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Description

This quiz covers the concepts of area calculations for semicircles and sectors, as well as arc length computations. Test your understanding of these geometric principles through a series of problems involving circles' measurements and properties. Challenge your skills with real-world applications related to arcs and sectors.

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