$\displaystyle sin(\frac{-3pi}{4}) cos(\frac{5pi}{6})$
Thanks
Didn't I tell you before to memorize certain trigonometric values? It seems you have not fulfilled this assignment.
sin(-3pi/4) = -sin(3pi/4) = -sin(pi/4) = ???
cos(5pi/6) = -cos(pi/6) = ???
Now what?
Note: If you're using LaTeX, feel free to put a slash in front of those "pi"s. Excellent results can be obtained.
Sorry, it's a little like you are just throwing darts.
On the first:
1) Where did the negative sign go?
2) $\displaystyle \sqrt{1}$?
On the second:
3) Where did the negative sign go?
4) Please note the difference between $\displaystyle \frac{\pi}{6}$ and $\displaystyle \frac{\pi}{3}$.
Look at a chart of values. Think it through. Don't just stab at it.
So the first on is$\displaystyle \frac{-\sqrt1}{2}$ and the second one is. $\displaystyle \frac{-\sqrt3} {2}$. I'm finding the (-)(Y value for $\displaystyle \frac{\pi}{4}$
and the X value for $\displaystyle \frac{\pi}{4}$ Is this correct. I'm not trying to take stabs at it, but i truely don't know how to do the problem.
You must MEMORIZE a few important values.
$\displaystyle 0\;\;\sin(0)\;=\;0\;\;\cos(0)\;=\;1$
$\displaystyle \frac{\pi}{6}\;\;\sin(\frac{\pi}{6})\;=\;\frac{1}{ 2}\;\;\cos(\frac{\pi}{6})\;=\;\frac{\sqrt{3}}{2}$
$\displaystyle \frac{\pi}{4}\;\;\sin(\frac{\pi}{4})\;=\;\frac{\sq rt{2}}{2}\;\;\cos(\frac{\pi}{4})\;=\;\frac{\sqrt{2 }}{2}$
$\displaystyle \frac{\pi}{3}\;\;\sin(\frac{\pi}{3})\;=\;\frac{\sq rt{3}}{2}\;\;\cos(\frac{\pi}{3})\;=\;\frac{1}{2}$
$\displaystyle \frac{\pi}{2}\;\;\sin(\frac{\pi}{2})\;=\;1\;\;\cos (\frac{\pi}{2})\;=\;0$
There is NO substitute for memorizing this tableau. Put it in your brain.
Note: You still have $\displaystyle \sqrt{1}$. Don't write things that make no sense.
So really what I'm trying to do when simplifying is getting the x or y of the above table?
So in the problem below I need to find the X or Y value?
Simplify $\displaystyle tan(\frac{-2\pi}{3})csc(\frac{3\pi}{4})$
Tan=$\displaystyle \frac{Y}{X}$ CSC=$\displaystyle \frac{1}{Y}$ Do I find the x or y value for tan and cosecant?