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Please help!!! Sketch one cycle of the graph of the sine function:
y=2sinπθ

User Estimate
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You can do a table for several values of tha angle (Ф).

But first you should remember some properties of the sine function.

1) Range: sine function goes from - 1 to + 1.

That means that 2 sin (πФ) goes from - 2 to + 2.

2) sine(0) = 0 => 2sin(π0) = 0

3) sine (π/2) = 1 =>

Ф = 0.5 => sin(π*0.5) = sin(π/2) = 1

=> 2sin(π*0.5) = 2

3) sin (-π/2) = - 1 =>

Ф = -0.5 => 2sin(-π/2) = -2

4) Periodicity:

The period of sine function is 2π

=> sin (πФ+ 2π) = sin(πФ)

Now you can do the table


Ф πФ sin(πФ) 2sin(πФ)

-1 -π sin(-π) 2sin(-π) = 0


-5/6 -5π/6 sin(-5π/6) 2sin(-5π/6) = -1


-1/2 -π/2 sin(-π/2) 2sin(-π/2) = -2


-1/6 -π/6 sin(-π/6) 2sin(-π/6) = -1


0 0 sin(0) 2sin(0) = 0


1/6 π/6 sin(π/6) 2sin(π/6) = 1


1/2 π/2 sin(π/2) 2sin(π/2) = 2


5/6 5π/6 sin(5π/6) 2sin(5π/6) = 1


1 π sin(π) 2sin(π) = 0


Then you can see that one cycle is from Ф = -1/2 to Ф = 1/2


And so you know that you can draw the function in that interval [-1/2, 1/2] and you already have some conspicuos values (from -2 to +2).


You can add some other points to do a better sketch.

User Apeirogon Prime
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