The problem states,

If sec(theta) = 3 with theta in QIV find cos(theta), sin(theta) and tan(theta).

Printable View

- February 5th 2009, 11:12 PMmoonman[SOLVED] Find Cos (theta), sin(theta), and tan(theta)
The problem states,

If sec(theta) = 3 with theta in QIV find cos(theta), sin(theta) and tan(theta). - February 6th 2009, 01:57 AMmathaddictRe:

is in the fourth quadrant so cos is positive .

- February 6th 2009, 02:55 PMmoonman
Thank you for helping :)

Can you explain in a little more detail how you got those answers? - February 6th 2009, 03:19 PMskeeter
you should know that secant is the reciprocal of cosine , so the fact that

should be immediate.

since is in quad IV , you should also know that and are both negative values.

there are two ways to determine the values of sine and tangent ...

1) use of reference triangles

sketch a reference right triangle in quad IV ... since , then the adjacent side = 1 and the hypotenuse = 3

the size of the opposite side =

since the opposite side has a downward direction, its value is .

2) use of Pythagorean identities ...

and, of course, you have to determine the correct sign from the quadrant info.