Sketch the graph of y=cos x in the range -pi < or equal to x < or equal to pi
Hence sketch the graph of y=|cos X| in the same range.
From my knowledge of sine and cosine waves i know what the graph will look like, and what the modulus graph will look like, what i dont know is how to prove it. i substituted pi and -pi into cosx and got -1 for both points on the graph, nbut i cant remember how t prove where the turning point is, i know its at (0,1) but i cant prove that without using prior knowledge,
You don't need to prove anything.
Originally Posted by ally79
The cos curve is the same as the sine curve shift forward by pi/2 radians. And the modulus of that curve is the same, except all the parts that are BELOW the x axis get reflected in the x axis, so that everything is above the axis.