# trig: sin (θ) is 1/5. The value of cos^2 (θ) can be written.....

• Jun 4th 2009, 08:19 PM
yoman360
trig: sin (θ) is 1/5. The value of cos^2 (θ) can be written.....
The value of sin (θ) is 1/5. The value of cos^2 (θ) can be written in the form 6(α^2). Express the value of α^2 (alpha squared) as a fraction in simplest form.
• Jun 4th 2009, 08:25 PM
Isomorphism
Quote:

Originally Posted by yoman360
The value of sin (θ) is 1/5. The value of cos^2 (θ) can be written in the form 6(α^2). Express the value of α^2 (alpha squared) as a fraction in simplest form.

$\cos ^2 \theta = 1 - \sin^2 \theta = 1 - \left( \frac15 \right)^2$

So if $6 \alpha ^2 = 1 - \left( \frac15 \right)^2$, what is $\alpha^2$?
• Jun 4th 2009, 09:31 PM
yoman360
Quote:

Originally Posted by Isomorphism
$\cos ^2 \theta = 1 - \sin^2 \theta = 1 - \left( \frac15 \right)^2$

So if $6 \alpha ^2 = 1 - \left( \frac15 \right)^2$, what is $\alpha^2$?

I don't know what it is thats why I'm asking.
• Jun 4th 2009, 10:07 PM
mr fantastic
Quote:

Originally Posted by Isomorphism
$\cos ^2 \theta = 1 - \sin^2 \theta = 1 - \left( \frac15 \right)^2$

So if $6 \alpha ^2 = 1 - \left( \frac15 \right)^2$, what is $\alpha^2$?

Quote:

Originally Posted by yoman360
I don't know what it is thats why I'm asking.

You are expected to show some effort at this stage. Where exactly are you stuck?

Can you do the arithmetic and simplify the right hand side of that expression? After doing that, what do you think the next step will be?
• Jun 6th 2009, 05:34 PM
yoman360
Quote:

Originally Posted by mr fantastic
You are expected to show some effort at this stage. Where exactly are you stuck?

Can you do the arithmetic and simplify the right hand side of that expression? After doing that, what do you think the next step will be?

I'm sorry I wasn't really looking at it i just saw what is a^2
• Jun 13th 2009, 11:08 PM
yoman360
Quote:

Originally Posted by Isomorphism
$\cos ^2 \theta = 1 - \sin^2 \theta = 1 - \left( \frac15 \right)^2$

So if $6 \alpha ^2 = 1 - \left( \frac15 \right)^2$, what is $\alpha^2$?

$6 \alpha ^2 = (25/25) - (1/25)$
$6 \alpha ^2 = 24/25$
$\alpha ^2 = 4/25$
• Jun 13th 2009, 11:20 PM
Isomorphism
Quote:

Originally Posted by yoman360
$6 \alpha ^2 = (25/25) - (1/25)$
$6 \alpha ^2 = 24/25$
$\alpha ^2 = 4/25$

Well Done (Clapping)