SOLUTION: if cosx=-12/13 and sin x>0, find tan(2x)

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Question 1056289: if cosx=-12/13 and sin x>0, find tan(2x)
Found 2 solutions by Magicmushroom, ikleyn:
Answer by Magicmushroom(1)   (Show Source): You can put this solution on YOUR website!
if cosx=-12/13 and sin x>0, find tan(2x)
Take the arccosine:

Plug in the value of x to find tan(2x)


Answer by ikleyn(52814)   (Show Source): You can put this solution on YOUR website!
.
if cosx=-12/13 and sin x>0, find tan(2x)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 

0.  The useful notice is: Since cos(x) is negative and sin(x) is positive, the angle "x" terminates in QII.


1.  Since cos(x) = , sin(x) =  =  =  =  =  = .

    The sign is "+" at the square root, since sine is positive, according to the condition.


2.  Then  =  =  = .


3.  Finally,  =  =  =  =  =  =  =  = .

Solved.

For more solved similar problems on calculating trig functions see the lessons
    - Calculating trigonometric functions of angles
    - Advanced problems on calculating trigonometric functions of angles
in this site.

Also, you have this free of charge online textbook in ALGEBRA-II in this site
    - ALGEBRA-II - YOUR ONLINE TEXTBOOK.

The referred lessons are the part of this online textbook under the topic "Trigonometry: Solved problems".


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