Respuesta :
The cosine repeats itself every 360 degrees, and it mirrors at 0 and 180 degrees. It inverts around 90 and 270.
So without using a calculator, you can tell that:
cos(520)=cos(520-360)=cos(160)
cos(160) = cos(180-20) = cos(180+20) = cos(200)
cos(160) is NOT equal to cos(20), it would be -cos(20).
cos(160) = -cos(20) = -cos(-20)
So C is the only one unequal.
So without using a calculator, you can tell that:
cos(520)=cos(520-360)=cos(160)
cos(160) = cos(180-20) = cos(180+20) = cos(200)
cos(160) is NOT equal to cos(20), it would be -cos(20).
cos(160) = -cos(20) = -cos(-20)
So C is the only one unequal.
Among the following options, for the trigonometric function the option (C) is not equal to cos(520°).
What is trigonometry?
Trigonometry is mainly concerned with specific functions of angles and their application to calculations. Trigonometry deals with the study of the relationship between the sides of a triangle (right-angled triangle) and its angles.
For the given situation,
The trigonometric function is cos(520°)
The cosine function is positive in I and IV quadrant.
The cosine function is an even function. So, cos(-θ) = cosθ
For cos θ = 0, 180, 360 ± θ, it will be cos θ and
For cos θ = 90, 270 ± θ, it will be sin θ
Now, cos(520°) = cos(360°+160°)
⇒ cos(160°)
cos(160°) = cos(180°-20°)
⇒ -cos(20°) [∵ cos θ is negative in II quadrant ]
cos(360°-160°) = cos(200°)
-cos(-20°) = -cos(20°) [∵ cosine is an even function]
Hence we can conclude that among the following options, for the trigonometric function the option (C) is not equal to cos(520°).
Learn more about trigonometry here
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