# IT. Expert System.

## C

### cos ( )

This function is used to calculate cosine.

Syntax:
`double cos( double arg );`

Example:

```#include

#include

int main()

{
float i = 0.314;
float j = 0.25;
float k = 6.25;
float sin_value = sin(i);
float cos_value = cos(i);
float tan_value = tan(i);
float sinh_value = sinh(j);
float cosh_value = cosh(j);
float tanh_value = tanh(j);
float log_value = log(k);
float log10_value = log10(k);
float exp_value = exp(k);

printf("The value of sin(%f) : %f \n", i, sin_value);
printf("The value of cos(%f) : %f \n", i, cos_value);
printf("The value of tan(%f) : %f \n", i, tan_value);
printf("The value of sinh(%f) : %f \n", j, sinh_value);
printf("The value of cosh(%f) : %f \n", j, cosh_value);
printf("The value of tanh(%f) : %f \n", j, tanh_value);
printf("The value of log(%f) : %f \n", k, log_value);
printf("The value of log10(%f) : %f \n",k,log10_value);
printf("The value of exp(%f) : %f \n",k, exp_value);
return 0;
}
Output:

The value of sin(0.314000) : 0.308866
The value of cos(0.314000) : 0.951106
The value of tan(0.314000) : 0.324744
The value of sinh(0.250000) : 0.252612
The value of cosh(0.250000) : 1.031413
The value of tanh(0.250000) : 0.244919
The value of log(6.250000) : 1.832582
The value of log10(6.250000) : 0.795880
The value of exp(6.250000) : 518.012817```

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