Math CentralQuandaries & Queries


Sketch the graphs of y= cos 2x and y= -0.5 over the domain -pi < x <pi. Determine the values of x where theses two graphs intersect. Use exact value.

I was wondering if someone could check it for me thanks!


Hi Kassandra,

I copied what you sent.


I agree with the values you have for where the graphs intersect, but the graph looks a little off. It's hard to be sure however because you didn't put units on the axes.

The maximum value of the cosine function is 1 and the minimum value is -1. Thus the bottom of the two valleys in your graph should be 1 unit below the x-axis. The horizontal line y = - 0.5 should be half way between the x-axis and the bottom of the valley. Your line is too close to the x-axis. If this is a homework assignment then before you turn it in you should put units on both the x and y axes.


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