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Mathematics 10 Online
OpenStudy (anonymous):

Trig identities?

OpenStudy (anonymous):

Find cot θ if \[\csc \theta=\frac{ \sqrt{17} }{ 4 }\] and tan θ > 0.

OpenStudy (anonymous):

\[1+\cot ^{2}\theta=\csc^{2}\theta\]

OpenStudy (anonymous):

so from the information provided

OpenStudy (anonymous):

so cot^2=sqrt(17)/4-1

OpenStudy (anonymous):

\[\csc \theta=\frac{ \sqrt{17} }{ 4 }\Rightarrow \csc^2 \theta = \frac{ 17 }{ 16 }\]by squaring both sides

OpenStudy (anonymous):

Okay so that would then be 1/16 if you subtract the 1?

OpenStudy (anonymous):

\[\cot ^{2}\theta= \frac{ 17 }{ 16 }-1\]

OpenStudy (anonymous):

\[\cot ^{2}\theta= \frac{ 1 }{ 16 }\]

OpenStudy (anonymous):

take the sqrt of both sides

OpenStudy (anonymous):

okay so I was right. so next you sqrt and get cot=sqrt(1)/4

OpenStudy (anonymous):

\[\cot=\frac{ \sqrt{1} }{ 4 }\]

OpenStudy (anonymous):

take the inverse of the function now and sqrt of 1 is 1

OpenStudy (anonymous):

thata = arctan(1/4), now i don't know at your level do you use +-sign or not

OpenStudy (anonymous):

yes I do

OpenStudy (anonymous):

and do you have to find all solutions, or is the question just on how to use the identity

OpenStudy (anonymous):

just that 1/4 was the correct answer

OpenStudy (anonymous):

ok good all the best

OpenStudy (anonymous):

thank you for you help

OpenStudy (anonymous):

but know that later at advanced levels there will be more than one solution for this equation

OpenStudy (anonymous):

anytime if you have any question let me know

OpenStudy (anonymous):

Just to know, what equation would I use to for Find tan θ if sec θ = sqrt(37)/6 and sin θ < 0.

OpenStudy (anonymous):

1+tan^2=sec^2?

OpenStudy (anonymous):

the same equation you just used but instead of cot you use tan and instead of csc you use sec

OpenStudy (anonymous):

i wrote it this way so you will never forget the identity

OpenStudy (anonymous):

okay thanks

OpenStudy (anonymous):

you are clever girl you learn quick

OpenStudy (anonymous):

i will put the identity for you

OpenStudy (anonymous):

\[1+\tan ^{2}\theta=\sec^{2}\theta\]

OpenStudy (anonymous):

thanks for all your help!

OpenStudy (anonymous):

recall the last identity\[1+\cot ^{2}\theta=\csc^{2}\theta\]

OpenStudy (anonymous):

all the best good luck

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