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# Core 3 Another Functions Question watch

1. Hi,

The questions says Solve |4cos3x|=2 for 0 degrees </= x </= 180 degrees
And so far I have two answers, 20 degrees and 40 degrees but they also have 80, 100, 140 and 160 degrees?

How did they get the rest of the answers?

2. You are solving 2 equations essentially.
.
As there is 3x inside the cosine function and not just x, you will have to look for solutions for 3x in the range .
You have to remember that the cosine curve is infinite but more importantly it is periodic, with a period of 360 degrees.
3. (Original post by B_9710)
You are solving 2 equations essentially.
.
As there is 3x inside the cosine function and not just x, you will have to look for solutions for 3x in the range .
You have to remember that the cosine curve is infinite but more importantly it is periodic, with a period of 360 degrees.
Ah I see! Thank you! I've got it now!

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