Without using table or calculator

Find the exact value of cos 105 leaving your answer in a surd form. I got (2sqrt 2-sqrt 6)/4 but I am not sure
in Trigonometry Answers by Level 4 User (7.5k points)

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2 Answers

??????? 105 deg ??????? thats 90+25 kosine go down tu zero at 90 deg, so 25 more deg meen kosine(105)=-sine(25 deg) sine(25 deg)=0.42261826174069944
by
cos105=cos(60+45)=cos60cos45-sin60sin45=(1/2)sqrt(2)/2-(sqrt(3)/2)(sqrt(2)/2)=

sqrt(2)/4-sqrt(6)/4=(sqrt(2)-sqrt(6))/4, so you were nearly right!
by Top Rated User (1.2m points)

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