Question

Prove identity: 1-cos2theta/sin2theta = tan theta

Answer 1

\(1-cos^2\theta\)=?

Answer 2

or is that a \(1−cos(2θ)=?\)

Answer 3

it's the second one

Answer 4

ok so then same for the bottom I take it?

Answer 5

I know that tan theta/2 = 1-cos theta/sin theta but I don't understand how to prove it

Answer 6

And yea, its the same

Answer 7

oh, well have you proven the tan theta over 2 already?

Answer 8

no, i just know that it's part of the half-angle identity

Answer 9

generally speaking, I don't know how to prove it at all knowing that

Answer 10

ohkkk

Answer 11

so let's see have you proved the double angle identity yet?

Answer 12

and what level? (so I know what cool toys I can use) =P

Answer 13

what do you mean by "what level"?

Answer 14

like, college class, high school, trig alg 1 complex var analysis

Answer 15

highschool trig

Answer 16

ohk well that sucks(no fun toys) hmm let me think.

Answer 17

lol

Answer 18

haha ok so what have you proved? let's start there

Answer 19

it's hard to know what I can use without going from scratch

Answer 20

i have no clue where to start...

Answer 21

like have you proved the squared identities?

Answer 22

it looks weird to replace it with a double angle identity

Answer 23

or anything yet?

Answer 24

no, I'm lost

Answer 25

ok well give me 15 minutes to get some coffee this will take 2 sheets of paper unfortunately so prepare yourself plus side, you'll be an expert once we are done

Answer 26

I hope so...

Answer 27

alright I have me some coffee let's do this

Answer 28

as a side note this is really useful http://en.wikipedia.org/wiki/Proofs_of_trigonometric_identities#Double-angle_identities

Answer 29

oh I have those..

Answer 30

which proofs do you haev already?

Answer 31

most of them...? I think so.

Answer 32

ok do you have half angle proof? double angle proof?

Answer 33

if you have half angle this is mind numbingly simple (plus side)

Answer 34

wait...i get it now...I think I know how to prove it

Answer 35

ok?

Answer 36

YAY, BUT: I have no clue where your mind is at, so if you have more questions just let me know =)

Answer 37

thanks for your patients thought...

Answer 38

np best of luck

Answer 39

I'll try. c: