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Mathematics 11 Online
OpenStudy (anonymous):

1 last trig problem

OpenStudy (anonymous):

jimthompson5910 (jim_thompson5910):

Try rewriting everything in terms of either sine or cosine

jimthompson5910 (jim_thompson5910):

eg: sec(x) = 1/cos(x)

OpenStudy (anonymous):

ahhhhh ok

OpenStudy (anonymous):

give me one sec

jimthompson5910 (jim_thompson5910):

also, when it comes to proving identities, you should only work on one side

jimthompson5910 (jim_thompson5910):

it might be easier to work on the right side

OpenStudy (anonymous):

\[q \cot q/\cos^{-1} -\sin(\theta)/expsec/\csc ^2\frac{ f1/\sec}{ ? } \]

OpenStudy (anonymous):

CRAP, i hate uploading equations on this website

OpenStudy (anonymous):

one sec, let me try again

OpenStudy (anonymous):

ok I got my answer, but when I try to put it in the equation on this website it messes up

OpenStudy (anonymous):

so i started working on the right side

jimthompson5910 (jim_thompson5910):

After trying out the right side, it's somewhat more complicated than I thought. So I'm going to work on the left side instead \[\Large \frac{\sec(\beta)}{\sin(\beta)}-\frac{\sin(\beta)}{\sec(\beta)} = \frac{\tan^2(\beta)+\cos^2(\beta)}{\tan(\beta)}\] \[\Large {\color{red}{\frac{\sec(\beta)}{\sec(\beta)}*}}\frac{\sec(\beta)}{\sin(\beta)}-\frac{\sin(\beta)}{\sec(\beta)} = \frac{\tan^2(\beta)+\cos^2(\beta)}{\tan(\beta)}\] \[\Large \frac{\sec^2(\beta)}{\sin(\beta)\sec(\beta)}-\frac{\sin(\beta)}{\sec(\beta)} = \frac{\tan^2(\beta)+\cos^2(\beta)}{\tan(\beta)}\] \[\Large \frac{\sec^2(\beta)}{\sin(\beta)\sec(\beta)}-{\color{red}{\frac{\sin(\beta)}{\sin(\beta)}}}*\frac{\sin(\beta)}{\sec(\beta)} = \frac{\tan^2(\beta)+\cos^2(\beta)}{\tan(\beta)}\] \[\Large \frac{\sec^2(\beta)}{\sin(\beta)\sec(\beta)}-\frac{\sin^2(\beta)}{\sin(\beta)\sec(\beta)} = \frac{\tan^2(\beta)+\cos^2(\beta)}{\tan(\beta)}\] \[\Large \frac{\sec^2(\beta)-\sin^2(\beta)}{\sin(\beta)\sec(\beta)} = \frac{\tan^2(\beta)+\cos^2(\beta)}{\tan(\beta)}\] Take a few minutes and look all that over. Then let me know when you're ready for the next step.

OpenStudy (anonymous):

wait I think I need to prove the right side of the equation not the left

jimthompson5910 (jim_thompson5910):

you can start on either side

OpenStudy (anonymous):

ok i get it

jimthompson5910 (jim_thompson5910):

just as long as you only work with one side

OpenStudy (anonymous):

alright is that it

OpenStudy (anonymous):

@jim_thompson5910

jimthompson5910 (jim_thompson5910):

look at the "Pythagorean Identities" on page 2

jimthompson5910 (jim_thompson5910):

what is sec^2 equal to?

OpenStudy (anonymous):

tan^2(theta)+1

jimthompson5910 (jim_thompson5910):

and what is sin^2 equal to?

OpenStudy (anonymous):

1-cos^2(theta)

jimthompson5910 (jim_thompson5910):

So, \[\Large \frac{\sec^2(\beta)-\sin^2(\beta)}{\sin(\beta)\sec(\beta)} = \frac{\tan^2(\beta)+\cos^2(\beta)}{\tan(\beta)}\] \[\Large \frac{\tan^2(\beta)+1-(1-\cos^2(\beta))}{\sin(\beta)\sec(\beta)} = \frac{\tan^2(\beta)+\cos^2(\beta)}{\tan(\beta)}\]

jimthompson5910 (jim_thompson5910):

simplify the numerator for the denominator, use the fact that sin*sec = sin*(1/cos) = sin/cos = ???

OpenStudy (anonymous):

Ok I did it, can you show me what you got

jimthompson5910 (jim_thompson5910):

when you simplified the numerator, what did you get?

OpenStudy (anonymous):

i wish I could show you, trust me, but I cant

jimthompson5910 (jim_thompson5910):

draw it out

jimthompson5910 (jim_thompson5910):

or type what you can

OpenStudy (anonymous):

I got back to where we started,

jimthompson5910 (jim_thompson5910):

\[\Large \tan^2(\beta)+1-(1-\cos^2(\beta))\] \[\Large \tan^2(\beta)+1-1+\cos^2(\beta)\] which becomes what?

OpenStudy (anonymous):

what the other side of the equation is

jimthompson5910 (jim_thompson5910):

yeah ultimately the goal is to get the left side equal to the right side

OpenStudy (anonymous):

what about the denominator

jimthompson5910 (jim_thompson5910):

what is sin(x)*sec(x) equal to?

jimthompson5910 (jim_thompson5910):

hint: look at "Tangent and Cotangent Identities" and "Reciprocal Identities" on that pdf

OpenStudy (anonymous):

ok I got it

OpenStudy (anonymous):

it is sinxsec

jimthompson5910 (jim_thompson5910):

sin(x)*sec(x) = sin(x)*(1/cos(x)) = sin(x)/cos(x) = ????

OpenStudy (anonymous):

tan

jimthompson5910 (jim_thompson5910):

yep

OpenStudy (anonymous):

alright thanks

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