Brenda P.
asked • 04/18/14-2cos x+square root of 3 = 0
solve the equation for 0 less than or equal to x less than 2 pie
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1 Expert Answer
Bob A. answered • 04/18/14
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Assuming you mean ( 0 <= x < 2Pi)
-2 Cos(x) + √3 = 0
-2 Cos(x) = - √3
Cos(x) = (-V3)/(-2) = √3/2
Can you get from there to the solution?
the possible results are x = Pi/6 , 11Pi/6
Brenda P.
uhmm i kind of confused i can you explain further?
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04/18/14
Brenda P.
i mean this 0≤ x < 2 pie
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04/18/14
Bob A.
Sure.
Once you get to
Cos(x) = (-V3)/(-2) = √3/2
you have isolated the variable. So now you need to find x.
Since taking the cos of x gives √3/2 [that is (√3) / 2 not √(3/2) ]
Then the inverse function will bring √3/2 back to x
[ function N = M then inverse function M - N ]
Cos(x) = √3/2
Inverse cos √3/2 = arc-cos √3/2 = cos-1 √3/2
Find the inverse cos of √3/2 on your calculator.
Then pick the ones that are between 0≤ x < 2 Pi
The two answers I gave you ( Pi/6 & 11Pi/6 ) are the exact values solving using maths.
The decimal values you get on your calculator will be approximate values since the calculator needs to round off Pi.
BTW - it is pi not pie
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04/18/14
Bob A.
OOPS - sorry
The [ function N = M then inverse function M - N ]
should be [ function N = M then inverse function M = N ]
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04/18/14
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Bob A.
04/18/14