Question

State the signs of the following trigonometric functions :

ii) cos 675​

Answer 1

Answer:

1/ √2

Step-by-step explanation:

Cos 675 = cos( 720 - 45)

= cos ( 2 × 360 - 45)

= cos ( 2π - 45)

That means this angle lies in the 4th quadrant

And the value if cos is positive if it's angle is in the 4th quadrant.

= cos 45

= 1/ √2

NOTE : we didn't change it to sine cause the function changes to sune only when there's an odd multiple of 1/ 2 in front of π.

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Hope this helps!