Trig Graphs & Identities
Sine and cosine waves have amplitude, period and shifts.
The rules
- For y = a sin(bx), amplitude = |a| and period = 2π / b.
- sin²x + cos²x = 1.
- tan x = sin x / cos x.
- A shift inside the parentheses moves the graph horizontally.
Watch out: Reading the period as b instead of 2π/b.
Worked example
What is the period of y = 3 sin(2x)?
- Period = 2π / 2.
- That equals π.
Answer: π
Try it yourself
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