Answer:
B
Step-by-step explanation:
sinΘ = [tex]\frac{6}{7}[/tex] = [tex]\frac{opposite}{hypotenuse}[/tex]
This is a right triangle with hypotenuse 7 and opposite side 6
Use Pythagoras' identity to find the adjacent side a
a² + 6² = 7²
a² + 36 = 49 ( subtract 36 from both sides )
a² = 13 ( take square root of both sides )
a = [tex]\sqrt{13}[/tex]
Then
cosΘ = [tex]\frac{adjacent}{hypotenuse}[/tex] = [tex]\frac{\sqrt{13} }{7}[/tex] → B
