Respuesta :

MathPhys

Answer:

-7/25

Step-by-step explanation:

tan θ = 4/3, π < θ < 3π/2

Using double angle formula:

cos(2θ) = (1 − tan²θ) / (1 + tan²θ)

cos(2θ) = (1 − (4/3)²) / (1 + (4/3)²)

cos(2θ) = (1 − 16/9) / (1 + 16/9)

cos(2θ) = (9 − 16) / (9 + 16)

cos(2θ) = -7 / 25

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