help with this (solving trig eqn, proving identity, etc)

isuckatmath

New member
Joined
Apr 27, 2006
Messages
1
1) How would you solve:

cosx=secx

2) prove this is true
sin2x+sin4x -tan3x=0
cos2x+cos4x

last one..

3) if R=v^2sin2x/g
and v=40 R110
solve for x
 

stapel

Super Moderator
Staff member
Joined
Feb 4, 2004
Messages
15,946
1) A good first step would be to convert everything to sines and cosines. What can you then do with the equation?

2) Your formatting is ambiguous. Do you mean the following?

. . . . .\(\displaystyle \large{\frac{\sin{(2x)}\,+\,\sin{(4x)}} {\cos{(2x)}\,+\,\cos{(4x)}}\, -\,\tan{(3x)}\, =\,0}\)

If so, what identities have you applied? How far have you gotten?

If not, please reply with corrections, showing your work so far.

3) Is the first equation the following?

. . . . .\(\displaystyle \large{R\, =\,\frac{v^2\,\sin{(2x)}}{g}}\)

Why is "v" given as being "40R100"? Is the "R" in the middle a typo? If not, why is there a "110" after it?

Thank you.

Eliz.
 
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