WEBVTT

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Here is the problem: Find sin, cos and tan of pi/2 on the unit circle.

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Unit circle values for 90° (pi/2 rad).

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Convert radians to degrees (multiply by 180/pi).

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Locate the terminal side: on the positive y-axis. Quadrantal angles land on an axis, so one coordinate is 0.

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Read the exact coordinates from the reference angle and apply the quadrant signs.

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Tangent equals sine divided by cosine.

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Reciprocal functions.

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So the answer is (cos theta, sin theta) equals (0, 1); tan theta equals undefined.

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90° (pi/2 rad) ends on the positive y-axis. sin theta equals 1, cos theta equals 0, tan theta equals undefined, csc theta equals 1, sec theta equals undefined, cot theta equals 0.

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cos squaredtheta plus sin squaredtheta equals 1 (must equal 1).