pre calc question :o help!?

Anthony H

New member
this question is unit circle related

you know how the sine and cosine values for pi/4 is square root 2/2 , square root 2/2?

well what if it was -pi/4.. what would the values for sine and cosine be now??

http://images.google.com/imgres?imgurl=https://www-old.math.gatech.edu/~sbishop/2401Spring08/UnitCircle.gif&imgrefurl=https://www-old.math.gatech.edu/~sbishop/2401Spring08/test3studyguide.html&usg=__-jSR0CLy-pjlWIAKhooOMM_cMso=&h=575&w=732&sz=52&hl=en&start=1&um=1&itbs=1&tbnid=b6OyxY_TLZ5-KM:&tbnh=111&tbnw=141&prev=/images%3Fq%3Dunit%2Bcircle%26um%3D1%26hl%3Den%26sa%3DN%26tbs%3Disch:1

so yeah I have no clue what to do, if you put a negative in front of it..
if cosine and sine for pi/2 are 0,1
then what are the values for - pi/2?

thanks
plus whats the general rule of thumb for figuring these out?
 
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