Respuesta :

C

using the cosine rule

cosC = ( a² + b² - c² ) / (2ab )

with a = 40, b = 41 and c = 9, then

cosC = ( 40² + 41² - 9² ) /( 2× 40 × 41 ) = [tex]\frac{3200}{3280}[/tex] = [tex]\frac{40}{41}[/tex] → C



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