# Perl Math - cos() Function

The Perl Math cos() function returns trigonometric cosine of an angle (angle should be in radians). In special cases it returns the following:

• If the argument is NaN or an infinity, then the result is NaN.

In the graph below, cos(x) vs x is plotted. ### Syntax

```cos(x)
```

### Parameters

 `x` Specify the angle in radian.

### Return Value

Returns the trigonometric cosine of an angle.

### Example:

In the example below, cos() function is used to find out the trigonometric cosine of an angle.

```use Math::Trig;

print("cos(pi/6) = ".cos(pi/6)."\n");
print("cos(pi/4) = ".cos(pi/4)."\n");
print("cos(pi/3) = ".cos(pi/3)."\n");
print("cos(Inf) = ".cos(Inf)."\n");
print("cos(-Inf) = ".cos(-Inf)."\n");
print("cos(NaN) = ".cos(NaN)."\n");
```

The output of the above code will be:

```cos(pi/6) = 0.866025403784439
cos(pi/4) = 0.707106781186548
cos(pi/3) = 0.5
cos(Inf) = NaN
cos(-Inf) = NaN
cos(NaN) = NaN
```

This function can also be used to calculate complex cosine of a complex number z. It is a function on complex plane, and has no branch cuts. Mathematically, it can be expressed as: ### Example:

In the example below, cos() function is used to find out the complex cosine of the given number.

```use Math::Complex;

\$z1 = 2 + 2*i;
\$z2 = 2;
\$z3 = 2*i;
print("cos(\$z1) = ".cos(\$z1)."\n");
print("cos(\$z2) = ".cos(\$z2)."\n");
print("cos(\$z3) = ".cos(\$z3)."\n");
```

The output of the above code will be:

```cos(2+2i) = -1.56562583531574-3.29789483631124i
cos(2) = -0.416146836547142
cos(2i) = 3.76219569108363
```

❮ Perl Math Functions

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