12 multiple-choice questions, progressively harder.
A proper sector has angle 5/45/45/4 radians and complete perimeter 262626 cm. What is its area?
Solution
Correct answer: D
Use the perimeter to determine the radius before finding area.
A sector has area 45π cm245\pi\text{ cm}^245π cm2 and selected arc length 9π9\pi9π cm. What is its radius?
Correct answer: B
The area is half radius times arc length.
A circle has radius 111111 cm and a chord of length 111111 cm. What is the area of the minor circular segment cut off by the chord?
Correct answer: C
The chord and two radii form an equilateral triangle, so the minor central angle is 60 degrees. Subtract the equilateral-triangle area from one sixth of the disk area.
A radius-141414 cm circle has a chord of length 14214\sqrt2142 cm. What is the complete perimeter of the minor circular segment?
Correct answer: A
The squared chord equals the sum of the squared radii, so the central triangle is right by the converse of Pythagoras. The minor arc is a quarter circumference.
An annulus has area 91π cm291\pi\text{ cm}^291π cm2 and total boundary length 26π26\pi26π cm. What is its inner radius?
The boundary sum determines the sum of radii. Use the area factorization to get their difference.
Two opposite minor segments are removed from a circle of radius 999 cm. Each removed segment has a 90∘90^\circ90∘ central angle. What is the area left between the two chords?
Each removed cap is a quarter-disk sector less a right triangle. Subtract both caps from the whole disk.
A sector of angle 444 radians is removed from a disk of radius 777 cm. The rest is kept as one closed sector. Which pair gives the kept area and complete perimeter?
Area 49π−98 cm249\pi-98\text{ cm}^249π−98 cm2.
Perimeter 14π−14 cm14\pi-14\text{ cm}14π−14 cm.
Area 98 cm298\text{ cm}^298 cm2.
Perimeter 14π−28 cm14\pi-28\text{ cm}14π−28 cm.
The kept angle is the remainder of a full turn. Include the two new straight edges in its perimeter.
A 90∘90^\circ90∘ sector of radius aaa and a 40∘40^\circ40∘ sector of radius bbb have equal areas. Both radii are positive and use the same unit. What is the ratio a:ba:ba:b?
Equal sector areas give an equation for the squared radii. Take the positive square-root ratio.
A quarter of an annulus has width 333 cm and area 51π/4 cm251\pi/4\text{ cm}^251π/4 cm2. What is the outer radius?
Multiply the quarter-ring area by four, then factor the difference of squared radii.
One 90∘90^\circ90∘ sector is removed from a disk. The kept 270∘270^\circ270∘ sector has area 75π cm275\pi\text{ cm}^275π cm2. What is its complete perimeter?
The area determines the radius. The kept boundary then has a three-quarter-circle arc and two radii.
A sector has radius 161616 cm and selected arc length 7π7\pi7π cm. What is its exact area?
With arc length already given, the area form using radius and arc length is direct.
A quarter of an annulus has inner radius 444 cm and complete perimeter (12+7π)(12+7\pi)(12+7π) cm. What is its exact area?
The complete perimeter includes two quarter-circular arcs and two connectors. Solve for the outer radius, then subtract the quarter-disk areas.
Reset this practice set?
This clears every answer you have given and starts the set again from question 1.