What is the value of cos 180°?
Cosine is a primary trigonometric function that represents the ratio between the lengths of perpendicular and hypotenuse in a right triangle.
Answer: The value of cos 180° is -1.
Let's find cos 180°.
We know that cos 180° = cos π
⇒ cos (π - θ ) = -cos θ
⇒ cos (π - 0º ) = -cos 0º
⇒ cos 0º = 1, but cos 180° lies in the second quadrant.
The value of the function cosine is positive in the first and fourth quadrant only.
Therefore, cos 180° is -1.