The Purplemath Forums

Please help me prove this trig identity

{{{ (1-secx)/(1+secx) = (cosx-1)/(cosx+1) }}}

this is the middle of a section and they have turned up the gears, i think if i am shown how i will be able to figure the rest out.

{{{ sqrt (1-1/a^2) }}}
sqrt1-1/1-a
a/a*1/1=a/a
sqrt (a^2-1)/a

hmm i see sqrt(1-1) 1/1 *a/a the a going back under the root gets ^2 theirfore sqrt (a^2 -1)....over a+a Denominators = a... simple fraction rules. i over thought that.

Thanks a 1000^2

I have a question that i am finding a different answer then one given. pleas explain where i am going wrong. given: cosec Theta = a so i know sin = 1/a asked to give remaining ratios. terminates in Quadrant 1 cos = sqrt (1-(1/a)^2) how do they come up with sqrt (a^2-1)/a :oops: i left school too ear...