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Theta is an angle in the unit circle that terminates on the x-axis. Which of the following options does not represent a possible measure for theta?

A) -5π
B) 5/2π
C) -360°
D) 540°
E) π

User Hien Tran
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1 Answer

7 votes

Final answer:

In the unit circle, an angle terminates on the x-axis if its measure is a multiple of π radians. For the given options, 5/2π radians does not terminate on the x-axis because it equals 450°, which lands the terminal side on the y-axis instead.

Step-by-step explanation:

The student's question is about determining which measure of an angle, represented by theta, does not represent an angle that terminates on the x-axis in the unit circle. An angle that terminates on the x-axis will have an angle measurement that is a multiple of π radians (180°), since a full circle is 2π radians (360°). Let's analyze the options provided:

  • A) -5π radians is a valid angle that terminates on the x-axis, as -5π is negative but represents a clockwise rotation that is a multiple of π.
  • B) 5/2π radians does not terminate on the x-axis because it equals 2.5π, which is equivalent to a 450° angle, landing the terminal side on the y-axis.
  • C) -360° or -1 full revolution, will indeed terminate on the x-axis after completing the circle in a clockwise direction.
  • D) 540° represents 1.5 revolutions and the angle will terminate on the x-axis.
  • E) π radians or 180° is a half rotation and terminates on the negative x-axis.

Therefore, the angle measurement that does not represent an angle terminating on the x-axis is option B) 5/2π radians.

User Ed Brannin
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