graphing trig functions
posted by bkue .
for graphing basic trig functions such as y=2sinx or y=1/3cosx, how do you know what the points are to graph with out using a calculator?
You can pick as many x points as you want. The more you plot, the easier it is to plot a smopoth and accurate curve.
For the y values that go with each x, you need a calculator, a special slide rule or a table of trig functions. Hardly anyone uses tables or slide rules anymore.
but for my quiz, i am not allowed a calculator
In that case, pick points that you know. For 2sinx, say, you know that
sin 0 = 0
sin pi/6 = .5
sin pi/4 = .707
sin pi/3 = .866
sin pi/2 = 1
and so on
If you know a few key values, you can sketch the graph easily. If you don't happen to know the value of pi/3, etc, use degrees. It's easy to plot x=0,30,45,60,90, etc.
How to find general solutions