SOLUTION: Given that x is measured in radians and x is greater than 10, find the smallest value of x such that {{{10cos((x+1)/(2)) = 3 }}} *Please answer as soon as possible bro :)

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Question 472803: Given that x is measured in radians and x is greater than 10, find the smallest value of x such that

10cos%28%28x%2B1%29%2F%282%29%29+=+3+

*Please answer as soon as possible bro :)

Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
10cos%28%28x%2B1%29%2F%282%29%29+=+3+
Divide both sides by 10

cos%28%28x%2B1%29%2F%282%29%29+=+.3+

Use inverse cosine on a calculator to get
the principle value of 1.266103873

That's the 1st quadrant value.  There is also a
4th quadrant answer of -1.266103873.  We will
have to consider both cases.

FIRST QUADRANT value of %28x%2B1%29%2F2

We can add 2pn and get 1st quadrant coterminal 
angles with that.

So we have 

%28x%2B1%29%2F2=1.266103873+%2B+2pi%2An

Solve for x:

Multiply through by 2

x%2B1=2.532207346+%2B+4pi%2An

Subtract 1 from both sides

x=1.532207346+%2B+4pi%2An

We set that greater than 10

1.532207346+%2B+4pi%2An%3E10

Solve for n:

4pi%2An%3E8.467792654

n%3E8.467792654%2F%284pi%29

n%3E.673845529

The smallest integer value of n is 1. 
So

x=1.532207346+%2B+4pi%2A1

x = 14.09857796

That may be the answer, but we have 
to consider the 4th quardrant value
as well to be sure.

---------

FOURTH QUADRANT value of %28x%2B1%29%2F2

We can add 2pn and get 4th quadrant coterminal 
angles with that.

So we have 

%28x%2B1%29%2F2=-1.266103873+%2B+2pi%2An

Solve for x:

Multiply through by 2

x%2B1=-2.532207346+%2B+4pi%2An

Subtract 1 from both sides

x=-3.532207346+%2B+4pi%2An

We set that greater than 10

-3.532207346+%2B+4pi%2An%3E10

Solve for n:

4pi%2An%3E13.53220735

n%3E1.076858845

The smallest integer value of n that satisfies
that is 2.  So

x=-1.532207346+%2B+4pi%2A2

x = 21.60053388
 
------------------

That is larger so the smallest solution for x
that satisfies

10cos%28%28x%2B1%29%2F%282%29%29+=+3+

and is greater than 10 is 14.09857796.

Edwin