Question

Find value of cos 7pi/4

Answer 1

Answer:

cos (7π\4) = cos (- π\4) = cos π\4 = √2/2

decimal form= 0.70710678

Step-by-step explanation:

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Answer 2

Answer:

cos 7pi/4 = 1/√2

Step-by-step explanation:

$\cos( \frac{7\pi}{4} ) = \cos( \frac{7 \times 180}{4} ) \\ = \cos(7 \times 45) \\ = \cos(315) \\ = \cos(360 - 45) \\ = \cos(45) \\ = \frac{1}{ \sqrt{2} }$

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