Geology & Seismic Waves: How Earthquakes Move Through the Earth
Geology -- Stresses in the earth compress rock formations and cause them to buckle into sinusoidal shapes.
Astronomy - Graph of number of sun spots that appear on the sun each year and context
Forensic science - blood pattern analysis
A theme park is building a portion of a roller coaster track in the shape of a sinusoid. You have been hired to calculate how enjoyable the ride is including the lengths of the horizontal and vertical support beams.