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Why is sin 360?

Published in Trigonometry Functions 1 min read

The question is likely asking: "Why is sin 360 degrees equal to zero?"

The value of sin 360° is zero because of its relationship to the unit circle.

Here's a breakdown:

  • The Unit Circle: Imagine a circle with a radius of 1 centered at the origin (0,0) of a coordinate plane.

  • Angles and Coordinates: An angle is formed by rotating a line from the positive x-axis counterclockwise. Where the line intersects the unit circle, we have coordinates (x, y).

  • Sine and Cosine: The x-coordinate of that point is the cosine of the angle (cos θ), and the y-coordinate is the sine of the angle (sin θ).

  • 360 Degrees: A 360-degree rotation brings us back to the starting point on the positive x-axis, which corresponds to the coordinates (1, 0).

  • Therefore: Since the y-coordinate represents the sine of the angle, and at 360 degrees the y-coordinate is 0, then sin 360° = 0. As the reference states, "The value of sin 360° is equal to the y-coordinate (0)."

Angle (Degrees) x-coordinate (cos) y-coordinate (sin)
0 1 0
90 0 1
180 -1 0
270 0 -1
360 1 0

In summary, sin 360° = 0 because a 360-degree angle on the unit circle corresponds to the point (1, 0), and the y-coordinate of this point (which represents the sine value) is 0.