
Doug C. answered 10/23/19
Math Tutor with Reputation to make difficult concepts understandable
-3U2 +4√3 U -4 = 0 is equivalent to:
3U2 -4√3 U +4 = 0 (multiply by -1)
Use the quadratic formula (easier than attempting to factor:)
U = 4√3 ± √(48 - 48)
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6
= 2√3/3
But in this case U is really csc x.
So csc x = 2√3/3.
Easier to work with sin, sin x = reciprocal of csc.
sinx = 3/2√3 = √3/2
x = arcsin (√3/2)
What angles between 0 and pi/2 (first quadrant) have a sin with a value of √3/2. Think 30-60-90 right triangle. x = 60 degrees or in radians π/3.