SOLUTION: Find all values of t in the interval [0, 2π] satisfying the given equation. 2 sin 2t-(sqrt 6) tan 2t = 0

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Question 851965: Find all values of t in the interval [0, 2π] satisfying the given equation.
2 sin 2t-(sqrt 6) tan 2t = 0

Answer by Edwin McCravy(20060) About Me  (Show Source):
You can put this solution on YOUR website!
Since we want t to be in the interval [0,2pi] we have to
find all values of 2t in [0,4pi] and interval.  That's because

since 0+%3C=+p+%3C=+2pi

then

     0+%3C=+2p+%3C=+4pi 

2sin%282t%29%22%22-%22%22sqrt%286%29tan%282t%29%22%22=%22%22%220%22

Substitute sin%282t%29%2Fcos%282t%29 for tan%282t%29

2sin%282t%29%22%22-%22%22sqrt%286%29%2Aexpr%28sin%282t%29%2Fcos%282t%29%29%22%22=%22%22%220%22

Multiply through by cos(2t) which we must require that
cos(2t) NOT EQUAL ZERO! because if it were zero we'd be
multiplying both sides of an equation by zero which is
not a valid operation.

2sin%282t%29cos%282t%29%22%22-%22%22sqrt%286%29%2Aexpr%28sin%282t%29%29%22%22=%22%22%220%22 with cos%282t%29%3C%3E0

Factor out sin(2t) 

sin%282t%29%282cos%282t%29-sqrt%286%29%29%22%22=%22%22%22%220%22%22

Use the zero-factor principle:

sin%282t%29=0;  2cos%282t%29-sqrt%286%29=0

Taking the first equation

sin(2t) = 0

2t = 0,pi,2pi,3pi,4pi

so divide them all by 2 to solve for the values of t

t = 0,pi%2F2,pi,3pi%2F2,2pi.

So there are 5 solutions in the interval [0,2pi].
And there may be more from the second equation.  

Taking the second equation:

2cos%282t%29-sqrt%286%29=0

2cos%282t%29=sqrt%286%29

cos%282t%29=sqrt%286%29%2F2

But sqrt%286%29%2F2 is more than 1, in fact it's like 1.224744871

and no cosine can ever exceed 1 (except in much higher mathematics
courses, but forget that for now).

So there were no additional solutions from the
second equation.

So the only possible solutions are:

t = 0,pi%2F2,pi,3pi%2F2,2pi.

We must also check to see if any are extraneous solutions 
because we multiplied through by cos%282t%29 and had to 
require that cos%282t%29%3C%3E0,

But cos%282t%29 is either 1 or -1 for each of those, never
0.  So 

t = 0,pi%2F2,pi,3pi%2F2,2pi.

are the only solutions in [0,2pi]

Edwin