Monday

March 30, 2015

March 30, 2015

Posted by **Hailey** on Thursday, April 10, 2008 at 8:43am.

1.) 2tanx-(1+tanx)^2 = -secx

2.) cos(x-330degrees)=1/2(3cosx-sinx)

*the is only over the 3*

3.)

1+cos2x/sinx=cotx

any help is greatly appreciated!!

- Math (Trig) typo edit -
**Hailey**, Thursday, April 10, 2008 at 8:49amis supposed to represent square root.

so for number 2

it's 1/2 (square root 3 cosx-sinx)

- Math (Trig) a.s.a.p, thanks! -
**Reiny**, Thursday, April 10, 2008 at 11:57am1.

LS = 2sinx/cosx - (1+sinx/cosx)^2

= 2sinx/cosx - ((cosx + sinx)/cosx)

= 2sinx/cosx - (cos^2 x + 2sinxcosx + sin^2 x)/cos^2 x

= (2sinxcosx -(1 + 2sinxcosx))/cos^2 x

= -1/cos^2 x

= -sec^2 x

you had -secx on the right side

I think you made a typo

2. LS = cosxcos330 + sinxsin330

but sin 330 = -sin30 = -1/2

and cos 330 = cos30 = √3/2

so above

= (√3/2)cosx - 1/2 sinx

= 1/2(√3 cosx - sinx)

= RS

Why don't you try the third one.

Change everything to sines and cosines

let me know how you did.

- Math (Trig) a.s.a.p, thanks! -
**Reiny**, Thursday, April 10, 2008 at 12:07pmfor the third one you had

1+cos2x/sinx=cotx

Your lack of brackets made this ambiguous.

I tried (1+cos2x)/sinx=cotx and tested with 40, did not work

I tried 1+cos^2 x/sinx=cotx and tested with 40, did not work

I tried 1+(cos2x/sinx)=cotx and tested with 40, did not work

check your typing of the question.

- Math (Trig) a.s.a.p, thanks! -

**Answer this Question**

**Related Questions**

Math - Im really struggling with these proving identities problems can somebody ...

Simplifying with Trigonometry Identities - Hi, I am a senior in High School ...

drwls - My previous question: Verify that (secx/sinx)*(cotx/cscx)=cscx is an ...

Pre-Calc - Trigonometric Identities Prove: (tanx + secx -1)/(tanx - secx + 1)= ...

Math (Trigonometry) - We are working on verifing identities using trigonomic ...

Trig Help - Prove the following: [1+sinx]/[1+cscx]=tanx/secx =[1+sinx]/[1+1/sinx...

Math please help quick - Which of the following are identities? Check all that ...

Trigonometry. - ( tanx/1-cotx )+ (cotx/1-tanx)= (1+secxcscx) Good one! ...

Precalculus/Trig - I can't seem to prove these trig identities and would really ...

Math - I'm only aloud to manipulate one side of the problem and the end result ...