## If cos 'theta' =1/2 the sin'theta' = WHAT?

Trigonometric ratios and functions, the unit circle, inverse trig functions, identities, trig graphs, etc.
rere
Posts: 2
Joined: Thu Jul 23, 2009 11:51 pm
Contact:

### If cos 'theta' =1/2 the sin'theta' = WHAT?

If 90 degrees < 'theta' <180 degrees what is equaled to 5 cos 'theta' sec 'theta'?

and another...

If cos 'theta' =1/2 the sin'theta' = WHAT?

thank you for any advice and help.

stapel_eliz
Posts: 1743
Joined: Mon Dec 08, 2008 4:22 pm
Contact:
rere wrote:If 90 degrees < 'theta' <180 degrees what is equaled to 5 cos 'theta' sec 'theta'?

I'm sorry, but I don't understand what this exercise is asking...? Are you supposed to find a range of value for the product of the 5, the cosine, and the secant? Or something else?

rere wrote:If cos 'theta' =1/2 the sin'theta' = WHAT?

Draw the right triangle. Label "adjacent" and "hypotenuse" sides with the values from the cosine ratio. Use the Pythagorean Theorem to find the value for the "opposite" side. Read off the value of the sine from the picture.

rere
Posts: 2
Joined: Thu Jul 23, 2009 11:51 pm
Contact:

### Re: If cos 'theta' =1/2 the sin'theta' = WHAT?

Yes, I am not sure what the question is asking for, I wrote it just as the problem said...Perhaps it is a typo
On the other, your advice helped me a lot. Thanks.
If f9x0=x^2-x, which of the following is equal to x^2+x
A. f(x)+x
B. f(x)-x
C. -f(x)
D. f(-x)
E. [f(x)]^2
Thanks

stapel_eliz
Posts: 1743
Joined: Mon Dec 08, 2008 4:22 pm
Contact:
rere wrote:If f9x0=x^2-x, which of the following is equal to x^2+x

I will guess that the first bit is supposed to be $f(x)\, =\, x^2\, -\, x.$

If so, try plugging $x^2\, -\, x$ into the various expressions, in places of $f(x)$, and find the one that matches.

pinkpuppi
Posts: 1
Joined: Mon Sep 07, 2009 6:46 pm
Contact:

### Re: If cos 'theta' =1/2 the sin'theta' = WHAT?

the square root of three over 2. remember SOH CAH TOA. if you make a triangle with 'theta' as your angle then plug in the cos in the appropriate spots. 1 in the adjacent leg and 2 on the hypotonuse. this would create a 30 60 90 triangle, meaning the only available side should be root three. then take that over two for sin because that would be the opposit angle. hope that makes sense!