# Find (x)

1. Feb 28, 2005

### no name

hey ....

find (x) ...
(sin x )^6 + (cos x) ^6 = 5/6 ( (sin x)^4 + (cos x)^4)

cheers

2. Feb 28, 2005

x= 22.5
.. I think

Last edited: Feb 28, 2005
3. Feb 28, 2005

### dextercioby

There's the same problem posted in the "Brain Teasers" Section where i've given the correct answers...

Daniel.

4. Feb 28, 2005

### HallsofIvy

If a problem involving trig functions does not specifically involve angle measured in degrees, x must be in "radians".

x= pi/8 is correct.

5. Feb 28, 2005

### Pseudo Statistic

How do you solve such a problem? (Involving both functions)

6. Mar 1, 2005

### dextercioby

Use that:$$\sin^{2}x=1-\cos^{2}x$$ and the fact that the powers in the equation are even...

Daniel.

7. Mar 1, 2005

### Zurtex

Erm, I think if you play around with it a bit you should be able to reduce it to :

$$\cos 4x = 0$$