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Mathematics 7 Online
OpenStudy (anonymous):

simplify the trigonometric expression *problem below*

OpenStudy (anonymous):

\[ \frac{ \sin x }{ \cos x }+\frac{ \cos x }{ \sin x}\]

OpenStudy (helder_edwin):

just add the fractions.

Parth (parthkohli):

That's like adding\[{x \over y} + {y\over x}\]

Parth (parthkohli):

\[ {\sin^2 x + \cos^2 x \over\sin x \cos x} \]

Parth (parthkohli):

Note that the numerator is 1.

OpenStudy (anonymous):

when i worked it out on a web calculator it gave me the answer tan(x) + cos(x) but i knew it was wrong because the answer was multiple choice

OpenStudy (anonymous):

my only choices are a. (sec x)(csc x) b. 1 c 2(sin x)(cos x)/sin^2x + cos^2x

Parth (parthkohli):

Since\[2\sin(x)\cos(x) = {\sin(2x)}\]we may say\[\sin(x)\cos(x) = 0.5\sin(2x)\]

Parth (parthkohli):

We already have,\[{1 \over 0.5\sin(2x)} \implies 2\sin(2x) \implies 4\sin(x)\cos(x)\]

OpenStudy (anonymous):

but which one of those answers does that come out to. im not sure how to get from that to one of my choices

OpenStudy (asnaseer):

@ParthKohli - you showed the first step correctly, i.e.:\[\frac{\sin x}{\cos x}+\frac{\cos x}{\sin x}={\sin^2 x + \cos^2 x \over\sin x \cos x}=\frac{1}{\sin x\cos x}\]

Parth (parthkohli):

I found a mistake.

OpenStudy (asnaseer):

the next step is to notice that:\[\frac{1}{\sin x}=cosec x\]and:\[\frac{1}{\cos x}=sec x\]

OpenStudy (anonymous):

yes. those are the only options given with the question being "which of the following is the correct simplification of the trigonometric expression?"

Parth (parthkohli):

I made a very elementary mistake...

Parth (parthkohli):

Ironically, I was doing the SAME question earlier this day and I did it correctly!

OpenStudy (asnaseer):

:)

OpenStudy (anonymous):

lol. its ok we all make mistakes sometimes.

OpenStudy (asnaseer):

@kizzfan911 you should now be able to work out the correct answer from the information given to you.

OpenStudy (anonymous):

ok. ill see what i can do.

OpenStudy (asnaseer):

hint:\[\frac{1}{\sin x\cos x}=\frac{1}{\sin x}\times\frac{1}{\cos x}\]

OpenStudy (anonymous):

i ended up getting sec(x)/sin(x)

OpenStudy (asnaseer):

use the two clues I gave above regarding what 1/sin x equals, and what 1/cos x equals

OpenStudy (asnaseer):

cosec(x) is the same as csc(x)

OpenStudy (anonymous):

0h ok. so its (sec x)(csc x)? i was entering it into the calculator wrong

OpenStudy (asnaseer):

yes :)

OpenStudy (anonymous):

thank you. your help is much appreciated.

OpenStudy (asnaseer):

yw :)

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