Question

Se sen x = -3/5 , x no 3 quadrante, então:
a) cos x = 4/5
b) cos x = -4/5
c) cos x = 3/5
d) cos x = -2/5

Answer 1

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Ola Juliam

sen²(x) + cos²(x) = 1

9/25 + cos²(x) = 25/25

cos²(x) = (25 - 9)/25 = 16/25

cos(x) - 4/5 (B)

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