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Mathematics 23 Online
OpenStudy (jadedry):

Find the general solution. (Trig - Tan/Cos problem.)

OpenStudy (jadedry):

\[\tan 2 \theta = \cot \theta\] I figured that: \[\tan 2 \theta = \tan (\pi -2 \theta)\] \[2 \theta = n \pi + \pi - 2 \theta\] \[4 \theta = n \pi + \pi\] General solution = \[\frac{ n \pi + \pi }{ 4 }\] My book says I'm wrong? How so? Thanks in advance!

OpenStudy (priyar):

tan2θ=−tan(π−2θ)

OpenStudy (jadedry):

Ah, so I need a minus sign on the right hand side?

OpenStudy (priyar):

but u don't need that step..

OpenStudy (jadedry):

? Is my first step incorrect then?

OpenStudy (priyar):

first change cot θ to tanθ

OpenStudy (priyar):

cot θ=tan(pi/2 - θ)

OpenStudy (jadedry):

Ah, so tan 2 theta = tan (pi/2 - 2 theta?)

OpenStudy (priyar):

now u'll have both sides tan..so u can equate the angles

OpenStudy (priyar):

No..read the statement carefully

OpenStudy (priyar):

right side (cotθ) can be changed to tan(pi/2-θ)..ok?

OpenStudy (jadedry):

Okay,

OpenStudy (jadedry):

ah! I got it, a bit slow this morning haha. I don't have to multiply cot by anything. Thanks for your assistance!

OpenStudy (priyar):

u r welcome..so can u do the rest?

OpenStudy (jadedry):

Yeah, I think so! \[\ 2 \theta = n \pi +\frac{ \pi }{ 2} - \theta\] \[3 \theta = n \pi + \pi/2 = \frac{ 2n \pi }{ 6 } + \frac{ \pi }{ 6 }\]

OpenStudy (jadedry):

which is the answer my book gave me. c:

OpenStudy (priyar):

GOOD JOB! i think u deserve a medal!

OpenStudy (jadedry):

Haha, thank you! I'll be sure to ping you if I need help in future. c: Thanks again!

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