If cos(x) = 1/4, x in quadrant 4, find the exact value of

tan[x - (pi/4)]

Results 1 to 3 of 3

- August 25th 2008, 03:04 AM #1

- Joined
- Jul 2008
- From
- NYC
- Posts
- 1,489

- August 25th 2008, 03:35 AM #2
Hello,

If x is in quadrant 4, then sin(x)<0.

We know that .

Hence .

Since the sine is negative,

---------------------------------

**Method #1**

Difference formula for cosine and sine (using ) :

Thus :

and

-------------------------------------

**Method #2**

Using difference formula for tangent :

...

- August 25th 2008, 08:52 PM #3

- Joined
- Jul 2008
- From
- NYC
- Posts
- 1,489