Why is Sin 90 Degrees Equal to 1? Explanation Using the Unit Circle

Learn why sin 90 degrees equals 1 based on the unit circle definition and trigonometry fundamentals.

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Sin 90 degrees equals 1 because of the unit circle in trigonometry. When the angle is 90 degrees, the point on the unit circle is (0, 1). Sine is defined as the y-coordinate of this point. Hence, sin 90° = 1.

FAQs & Answers

  1. What is the unit circle in trigonometry? The unit circle is a circle with a radius of 1 centered at the origin of the coordinate plane, used to define sine, cosine, and tangent values for all angles.
  2. Why does sin 90 degrees equal 1? Sin 90 degrees equals 1 because, on the unit circle, the point corresponding to 90 degrees is (0, 1), and sine is the y-coordinate of that point.
  3. How is sine defined using the unit circle? Sine of an angle is defined as the y-coordinate of the point on the unit circle that corresponds to that angle.