Homework Help: trig

Posted by spencer on Tuesday, April 13, 2010 at 8:10pm.

using the trigonometric identities find the exact (radical form) value of cos (105 degrees)

trig - Reiny, Tuesday, April 13, 2010 at 8:39pm
cos 105°
= cos(60+45)
= cos60cos45 - sin60sin45
= (1/2)(√2/2) - (√3/2)(√2/2)
= (√2 - √6)/4
trig - Reiny, Tuesday, April 13, 2010 at 8:40pm
cos 105°
= cos(60+45)
= cos60cos45 - sin60sin45
= (1/2)(√2/2) - (√3/2)(√2/2)
= (√2 - √6)/4
trig - vian, Thursday, July 19, 2012 at 10:52pm
cos195

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