DDesmos SAT Prep
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Trig: Period & Amplitude

Read amplitude and period straight off a sine or cosine graph.

The Desmos trick

Graph the trig function and trace along it (or use the table) to read the maximum value (amplitude + midline) and the horizontal distance between peaks (period) directly, without memorizing formulas.

  • Type the function exactly: y = 4cos(2x)
  • Check the mode: click the wrench/settings icon to switch between radians and degrees to match the problem
  • Use the table to find the maximum value, or trace the curve to spot the first peak for the period

Practice questions

Q1What is the amplitude and period of y = 4cos(2x)?
Medium
Q2The function h(t) = 3sin((π/6)t) + 10 models the height, in meters, of…
Medium
Q3What is the amplitude and period of y = 5sin(3x)?
Easy
Q4The function h(t) = 2cos((π/4)t) + 6 models a height in meters. What i…
Medium