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Answer is E.By similar triangles and Pythagoras:cos(phi/2) = (sqrt(2) + sqrt(3) )/ (3*sqrt(2)/2 + sqrt(3)) = sqrt(6)/3cos(phi) = 2cos^2(phi/2)-1 = 1/3
Answer is E.
ReplyDeleteBy similar triangles and Pythagoras:
cos(phi/2) = (sqrt(2) + sqrt(3) )/ (3*sqrt(2)/2 + sqrt(3)) = sqrt(6)/3
cos(phi) = 2cos^2(phi/2)-1 = 1/3