PURPOSE: To remind students of the definitions of sine and cosine.
DESCRIPTION: Slowly rotate the unit circle of radius R. Students can easily observe the opposite side and the adjacent side as the angle is changed. This provides a dynamic sense of the values of the sine and cosine in the first two quadrants.
REFERENCES: (PIRA unavailable.)
EQUIPMENT: Disc-mounting rod assembly, wood stand with table clamp, metal stand with right-angle clamp, two stick pointers, nail; assembled as photographed on request.
SETUP TIME: 5 min.
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