C clutch Dec 2008 7 0 Dec 14, 2008 #1 i have to evaluate without using a calculator cos 165 can someone help me out

euclid2 May 2008 400 82 Ottawa, Canada Dec 14, 2008 #2 clutch said: i have to evaluate without using a calculator cos 165 can someone help me out Click to expand... cos165=cos(120+45) =cos120cos45-sin120sin45 =(-1/2)(sqrt2/2)-(sqrt3/2)(sqrt2/2) =-sqrt2-sqrt4/6 is that what you need? Reactions: clutch

clutch said: i have to evaluate without using a calculator cos 165 can someone help me out Click to expand... cos165=cos(120+45) =cos120cos45-sin120sin45 =(-1/2)(sqrt2/2)-(sqrt3/2)(sqrt2/2) =-sqrt2-sqrt4/6 is that what you need?