Question

se sen x= 0.86 qual o valor de cos x?

Answer 1

Usando o teorema fundamental :
$sen {x}^{2} + cos {x}^{2} = 1 \\ {(0.86)}^{2} + cos {x}^{2} = 1 \\ cos {x}^{2} = 1 - 0.7396 \\ cos {x}^{2} = 0.2604 \\ cos = \sqrt{0.2604} \\ cos x = 0.51$