Question

verify the trig equation by sub identities to match the right side
cot x sec^4x=cot x + 2 tan x + tan^3x

Answer 1

Did you try it?

Answer 2

yea Im just so lost with this hsit because everyone is dofferent

Answer 3

like its saying ignore the right side and make the left side equal to the right

Answer 4

and I have my identities

Answer 5

Kind of, yes... :) this isn't "solving an equation" which is what you are used to. This is "prove the identity", so the goal is to show - using algebra and trig identities that you arleady have - that the expression on the left is equivalent to the one on the right.

So you need to work FROM one side, TO the other, and show step by step what gets you there.

Answer 6

ok its saying work the left side to show its equal to the right

Answer 7

\(\Large \cot x \sec^4x=\cot x + 2 \tan x + \tan^3x\)

OK, I notice that there is a product on the left and I need to get to a sum on the right.

The sum on the right has a cotx in it, just like I start with on the left. But it has all that tangent stuff too, right?

Answer 8

ok I see what you mean

Answer 9

can we just cancel them?

Answer 10

So I need to get rid of sec^4, and get me some tangents. Can you think of an identity that relates secant and tangent?

And btw, I see that it seems to imply go left -> right... I find that kind of silly. As long as you go FROM one side TO the other, you can start on whichever you want. You can always reverse what you did to show it from either side.

Answer 11

NO, there is no "cancelling"... remember, NOT an equation. We are going FROM one side TO the other.

We want to start on the left, and find algebraic steps to show:

\(\Large \cot x \sec^4x=.......\\
\Large ..................=\\
\Large ..................=\\
\Large ..................=\\
\Large \cot x + 2 \tan x + \tan^3x\)

Just need to fill in the steps!

Answer 12

is it one of the pythagreom identities?

Answer 13

yes, that's what i'm thinking....

Answer 14

i already solved this question last one month ago :)
http://openstudy.com/study#/updates/51effc9be4b0c8f6bc34712d

Answer 15

1+tan^2u=sec^2u

Answer 16

ok now this is were I get really confused like what the heck am I supposed to do with that long thing

Answer 17

right... go check out @RadEn 's link, that's pretty much where I was going with it.

But try it yourself first!

Answer 18

kinda confused at that if you don't mind can we take it step by step because I have like 4 more I have to do after this

Answer 19

and they don't get easier

Answer 20

ok, you have:

\(\Large \cot x \sec^4x\)

Now, \(\Large \sec^4x=(sec^2x)^2\) right?

Answer 21

ok where did the exponent of 2 come from on the right side I see the sec^2x is part of the identity

Answer 22

hang on, phone...

Answer 23

so sorry, I have to go....

Answer 24

ok thanks fir trying