12 multiple-choice questions, progressively harder.
Which condition defines a central angle of one radian?
Solution
Correct answer: B
One radian uses an arc one radius long. A straight chord is a different length, and a full circumference contains more than one radius.
A selected arc is 141414 cm long in a circle of radius 777 cm. What is its central angle in radians?
Correct answer: D
Divide the arc length by the radius in the same units.
Convert 60∘60^\circ60∘ to radians.
Correct answer: A
A 60-degree turn is one third of a half-turn.
Convert 5π4\tfrac{5\pi}{4}45π radians to degrees.
Correct answer: C
Multiply the radian measure by 180 divided by pi.
Find the length of a 45∘45^\circ45∘ arc in a circle of radius 121212 cm.
The arc takes one eighth of the full circumference.
A selected central turn is 35\tfrac3553 radian in a circle of radius 101010 m. Find the arc length.
The arc is three fifths of a radius long.
The same central angle cuts an arc of 555 cm in a circle of radius 666 cm. Find the matching arc length in a circle of radius 181818 cm.
The radius is multiplied by 3, so the corresponding arc is multiplied by 3.
A circle has positive radius. How far along it does a zero central turn travel?
A zero turn does not move from the starting point.
Which is the radian measure of one full turn?
A full circumference is two pi radii long. Centimeters measure length, and pi radians is only a half-turn.
An arc length and radius are both measured in meters. What happens to the length units in the quotient used for radian measure?
Both numerator and denominator use the same length unit. The unit factor cancels, leaving a dimensionless numerical ratio; radians identify its use as an angle measure.
A circle has diameter 202020 cm. Find the length of its selected 126∘126^\circ126∘ arc.
Use half the diameter as the radius.
A selected arc has central turn 7π8\tfrac{7\pi}{8}87π radians. What kind of arc is it?
Compare the turn with a half-turn.
The selected turn is smaller than a half-turn, so the arc is minor.
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