SOLUTION: compute sin(18) + sin(42) + sin(78) + sin (102) / cos(12)

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Question 1156524: compute sin(18) + sin(42) + sin(78) + sin (102) / cos(12)
Answer by greenestamps(13219) About Me  (Show Source):
You can put this solution on YOUR website!


Use the identities for sin(A+B) and sin(A-B) and simplify....

%28sin%2818%29+%2B+sin%2842%29+%2B+sin%2878%29+%2B+sin+%28102%29%29+%2F+cos%2812%29





%282%2Asin%2830%29cos%2812%29%2B2%28sin%2890%29cos%2812%29%29%29%2Fcos%2812%29

2sin%2830%29%2B2sin%2890%29+=+2%281%2F2%29%2B2%281%29+=+1%2B2+=+3

ANSWER: 3