What is the difference between Cos(1/2)= and arcCos(1/2)=, why are they both equal to pi/3

in Cos(1/2) you are asking for the cosine of the angle which is 1/2 radian

using my calculator, I got .87758....

in arcCos(1/2) , you are asking for an angle whose cosine is 1/2
in degrees that would be 60° or π/3 in radians

They are NOT the same

however, cos-1(1/2) is just another way to write arccos(1/2)

The difference between "Cos(1/2)=" and "arcCos(1/2)=" lies in the context and notation used.

1. Cos(1/2) corresponds to the cosine function evaluated at 1/2. Here, "Cos" stands for cosine, and the expression "1/2" represents the angle in radians. In this case, Cos(1/2) means finding the cosine of an angle that measures 1/2 radian.

2. arcCos(1/2) corresponds to the inverse cosine function evaluated at 1/2. Here, "arcCos" stands for the inverse cosine function, which is also known as arccosine or cos^{-1}. The expression "1/2" represents the value of the cosine function. In this case, arcCos(1/2) means finding the angle whose cosine is equal to 1/2.

Now, why are both Cos(1/2) and arcCos(1/2) equal to pi/3?

The cosine of an angle measures the ratio of the adjacent side to the hypotenuse in a right triangle. When you evaluate Cos(1/2), you are finding the cosine of an angle that measures 1/2 radian. In this case, the adjacent side and hypotenuse are both equal to 1. By the definition of cosine, Cos(1/2) = 1/1 = 1.

On the other hand, the inverse cosine function arcCos(x) gives the angle (between 0 and pi) whose cosine is equal to x. In this case, arcCos(1/2) represents the angle whose cosine is equal to 1/2. By the definition of the inverse cosine, arcCos(1/2) = pi/3, as this is the angle between 0 and pi for which Cos(pi/3) = 1/2.

So, even though the notation and context differ between Cos(1/2) and arcCos(1/2), both are equal to pi/3, which explains their equality.

The difference between "Cos(1/2)" and "arcCos(1/2)" lies in their mathematical definitions and functions.

1. Cos(1/2): This expression represents the cosine of the angle 1/2. In trigonometry, the cosine function calculates the ratio of the adjacent side of a right-angled triangle to the hypotenuse. However, in this case, the value 1/2 does not represent an angle in degrees or radians. It might be a typographical error or a misunderstanding.

2. arcCos(1/2): This expression represents the inverse cosine or arc cosine of the value 1/2. The arccosine function, or inverse cosine, is the mathematical operation that returns the angle whose cosine is equal to the given value. In this case, the input is 1/2, and the output is the angle whose cosine is 1/2.

Now, to explain why both "Cos(1/2)" and "arcCos(1/2)" are equal to π/3:

The cosine function has limited values within the range of -1 and 1. At certain angles, the cosine function evaluates to 1/2. One such angle is π/3 (pi/3). This means that the cosine of π/3 is equal to 1/2.

When we compute "arcCos(1/2)" using the inverse cosine function, it gives us the angle whose cosine is 1/2. By definition, the arc cosine of 1/2 is π/3 (pi/3).

Therefore, both "Cos(1/2)" and "arcCos(1/2)" are equal to π/3 (pi/3) since they represent the cosine of π/3 and the angle whose cosine is 1/2, respectively.