Respostas

2014-04-22T17:55:22-03:00
A) Sen 105° = sen (60 + 45)
= sen60.cos45 + sen45.cos60
= √3/2 . √2/2 + √2/2 . 1/2
= (
√6 + √2)/4

B)  sen 15º = sen (60 - 45)
= sen60.cos45 - sen45.cos60
= √3/2 . √2/2 - √2/2 . 1/2
= (
√6 - √2)/4

C) cos 75º = cos (45 + 30)
= cos45 . cos30 - sen45 . sen30
= √2/2 . √3/2 - √2/2 . 1/2
= (√6 - √2) / 4









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