Respuesta :

MathPhys

Answer:

20/29

Step-by-step explanation:

sin θ = 21/29

Use Pythagorean identity:

sin² θ + cos² θ = 1

(21/29)² + cos² θ = 1

441/841 + cos² θ = 1

cos² θ = 400/841

cos θ = ±20/29

Since 0° < θ < 90°, cos θ > 0.  So cos θ = 20/29.

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