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JavaScript JavaScript Basics (Retired) Working With Numbers The Math Object

Michael McKenna
Michael McKenna
3,451 Points

Fun fact

For those who are not yet math literate, arccos is (1/cos) or the equivalent secant. That is all =)

Adam Nettel
Adam Nettel
460 Points

Not correct. arccos may be written as cos^-1, but confusingly that is not intended to mean 1/cos or sec. Arccos, arcsin, etc are only used to find the angle from a trigonometric ratio, which is the "inverse" of using cos, sin, etc to find the trigonometric ratio from an angle.

1 Answer

Balazs Peak
Balazs Peak
46,160 Points

Adam Nettel has the point :D arccos is the inverse function of cos. Sometimes, you want to calculate the cosine of an angle, right? But maybe even more frequently, you want to tell about a number, which angle's cosine it is. Now, THAT is exactly what arccos is used for.

IF the following equation is true: cos( X ) = Y

THEN cos ( Y ) = X

Example: cos ( X ) = 0.5 What is X? Solution: arccos(0.5) = Pi / 3 = 3.14 / 3 (approximately) You can also give the solution in degrees, then it would be 60