+0  
 
0
3398
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avatar+4 

$$\underset{\,\,\,\,{\textcolor[rgb]{0.66,0.66,0.66}{\rightarrow {\mathtt{sin0, cos}}}}}{{solve}}{\left(\begin{array}{l}{\mathtt{Sin0}}={{\mathtt{5}}}^{{\mathtt{7}}}\\
{cos}\left(=\mathrm{ERROR}\end{array}\right)} \Rightarrow \left\{ \begin{array}{l}{\mathtt{sin0}} = {\mathtt{78\,125}}\\
{cos}\left( = {\mathtt{ERROR}}\\
\end{array} \right\}$$
What is csc if sin =5/7

 Jun 12, 2014

Best Answer 

 #2
avatar+118677 
+10

Thanks Chris, the trig identity works fine - Here's another take on the problem.

ok sine is postitive for theta must be in the first or second quadrant.  This just means that Cosθ can be positive or negative.  To find the one in the first quad just draw a right angled triange.  Put your info on it and find the third side using Pythagoras' Theorems.

Like this.  So reading straight from the triangle        $$cos\theta=\pm \frac{2\sqrt6}{7}$$

 Jun 12, 2014
 #1
avatar+129852 
+5

Using a trig identity, we have

1 - (5/7)^2  = (cosx)^2

1 - 25/49 = (cosx)^2

24/49 = (cosx)^2        take the square root of both sides, we have

±√(24)/7 =  ±[2√(6)]/7   = cosx

This makes sense...the sine is positive in the first two quadrants, so the cos is positive in the first, but negative ni the second.......

 Jun 12, 2014
 #2
avatar+118677 
+10
Best Answer

Thanks Chris, the trig identity works fine - Here's another take on the problem.

ok sine is postitive for theta must be in the first or second quadrant.  This just means that Cosθ can be positive or negative.  To find the one in the first quad just draw a right angled triange.  Put your info on it and find the third side using Pythagoras' Theorems.

Like this.  So reading straight from the triangle        $$cos\theta=\pm \frac{2\sqrt6}{7}$$

Melody Jun 12, 2014
 #3
avatar+2353 
0

reinout-g Jun 12, 2014

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