25.3.3 Reduction Formulas: Using the Circle's Symmetry
25.3 Trig Functions on the Unit Circle and the Reduction Formulas
Point 3 of 4
25.3.3 Reduction Formulas: Using the Circle's Symmetry
Core idea
Add π, flip to the opposite, or go a full turn, and the point on the circle just reflects into a symmetric spot, so the value only swaps a sign or swaps a name.
Module goal. We upgrade trig functions from the right triangle to the coordinates of a point on the unit circle, so they make sense for any angle, and we use the circle's symmetry to read off the reduction formulas all at once.
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