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Mathematics 8 Online
OpenStudy (anonymous):

Can anyone explain how to prove this using trigometric identidies?

OpenStudy (anonymous):

(sec(x)+csc(x))/(1+tan(x)) = csc(x) prove it by manipulating only the left side of the equation

OpenStudy (superdavesuper):

easiest way is probably start by expressing everything on the left in terms of sin(x) and cos(x)....what will u get?

OpenStudy (anonymous):

(1/cos(x))+(1/sin(x))

OpenStudy (superdavesuper):

yup yup....that would be for the top part....how about the bottom? tanx=sinx/cosx right? :)

OpenStudy (anonymous):

yeah, so then do you multiply the top like this? (1/cos(x))(cos(x)/sin(x)) + (1/sin(x))(cos(x)/sin(x))

OpenStudy (superdavesuper):

nah i would just multiply both top n bottom by (sinx)(cosx)....that will get rid of the division in the top first...

OpenStudy (anonymous):

???

OpenStudy (superdavesuper):

(1/cos(x))(cos(x)(sin(x)) + (1/sin(x))(cos(x)(sin(x)) = sin(x) + cos(x) right? need to do the same multiplication to the bottom part though

OpenStudy (anonymous):

how do you do this while only manipulating the left side?

OpenStudy (superdavesuper):

by multiplying the same thing (cosx)(sinx) to BOTH top n bottom on the left

OpenStudy (anonymous):

so... ((1/cosx)(cosx)(sinx)+(1/sinx)(cosx)(sinx))/(1(sinx)(cosx)+((sinx)/(cosx))(sinx)(cosx)???

OpenStudy (superdavesuper):

hahahahahahahaa yes - i would probably have splitted the top n bottom up n do them separately but u got it :)

OpenStudy (anonymous):

does it become... ((((sinx)(cosx))/cosx)+(1/sinx)(sinx)(cosx))/(sinx)(cosx)+sin^2x

OpenStudy (superdavesuper):

lets do it separately okay? im getting a head ache from reading lol top part is done: it would simplify to sinx+cosx okay?

OpenStudy (superdavesuper):

n u got the bottom part right (sinx)(cosx) + (sinx)^2

OpenStudy (superdavesuper):

see anyhting similar between top n bottom? ;)

OpenStudy (anonymous):

okay

OpenStudy (anonymous):

um the bottom becomes (sinx)(cosx+sinx) and that cancels out with the the sinx+cosx on the top

OpenStudy (anonymous):

does that mean your left with 1/sinx which equals cscx?

OpenStudy (superdavesuper):

Bingo :)

OpenStudy (anonymous):

thank you!!!

OpenStudy (superdavesuper):

welcome - u did most of the work anyway lol

OpenStudy (anonymous):

i have the most troble with trig proofs so thank you soo much!!!

OpenStudy (superdavesuper):

n thanx for staying w the prob. a lot of ppl would simply ask for the proof itself :)

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