Trig help

AllanB

New member
Joined
Nov 29, 2006
Messages
3
Interval [0, 2pi]
2*cos^2 x pi sqrt(3)*cos x = 0

The solution set I got for the answer was:
Solution set: {pi/6, pi/2,3pi/2, 11pi/6}

I was told the correct solution set was:
{pi/6, pi/2,pi,3pi/2, 11pi/6}


The explanation was as follows:

a)cos x = 0
Over the inteval [0, 2pi] the equation cos x = 0 has two solutions: x = pi/2, 3pi/2

b)2*cos x pi sqrt(3) = 0
cos x = sqrt(3)/2

Over the inteval [0, 2pi] this equation has two solutions. The angles are in quadrants I and IV and have a reference angle pi/6, the two angles are pi/6, 11pi/6.

Solution set: {pi/6, pi/2, pi, 3pi/2, 11pi/6}

I don't understand why PI is part of the solution set.
 
Never Mind. I FINALLY got a reply back from my instructor. She had made a typo, and pi does not belong in the solution set.
 
Top