Unit 4 · 5 lessons

Trigonometric Functions

Retire the degree: radian measure, the unit circle in radians, exact values, sinusoidal transformations, and the three reciprocal trig functions.

51 practice questions
44 flashcards
3 interactive lessons

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Lessons

1Radian MeasureA radian measures an angle by the arc it cuts, not by an arbitrary 360-part division of a circle — and once you switch, arc length, sector area, and rates of rotation all become one-line formulas.10 questions
2The Unit Circle and Exact ValuesEvery trig value you will ever be asked for without a calculator comes from one circle of radius 1, two special triangles, and a rule about signs.Interactive10 questions
3Trigonometric Graphs and TransformationsUnroll the unit circle onto an axis and you get the sine, cosine, and tangent graphs — then the familiar four transformation parameters reshape them, with period now measured in multiples of pi.Interactive10 questions
4Modelling with Sinusoidal FunctionsBuild $y = a sin (k (x - d)) + c$ or $y = a cos (k (x - d)) + c$ models from descriptions and data — Ferris wheels, tides, daylight, temperature — then use them to predict values and to find when a given value occurs.Interactive11 questions
5Reciprocal Trigonometric FunctionsCosecant, secant, and cotangent are one over sine, cosine, and tangent — and every feature of their graphs can be predicted from the graph underneath.10 questions