For a better understanding, we always recommend you to learn the basic topics of C programming listed below:

In this C program, we have to find the area of a scalene triangle. The scalene triangle is a triangle in which they have three unequal sides. The triangle that is drawn at random would be scalene. The interior angles of the scalene triangle are always different since they have unequal sides.

In this C program, we need to find the triangle area, given the sides and angle between them. Normally we used to calculate the area of a scalene triangle using the equation, **area = 1/2 X base X height**. Here we are using another well-known formula and applying it in this program.

'`Area = (s1 * s2 * sin((M_PI / 180) * angle)) / 2`

'

where **s1,s2** are adjacent sides of the triangle and **angle** is the angle between those sides. To covert the angle in degrees to radian use the formula **(M_PI / 180) X angle, M_PI** is a Constant defined in **math.h** header file that contains the value 3.14. And use the radian value of the angle in `sin()`

function to calculate the area.

In this c program, we first accept the triangle sides; also, we ask the user to enter the angle between them, which we need to calculate the area. After getting the triangle's desired angle and sides, we apply our formula to calculate the triangle area. Here we are using the sine(angle) to find the area of the triangle. After calculation of the area, display the output of the C program using the float data type.

**STEP 1:** Include the header files to use the built-in functions in the C program.

**STEP 2:** Declare the variable **s1, s2**, **angle** as integer, and **area** as a Float.

**STEP 3:** Accept the side1 of a triangle into the variable **s1**.

**STEP 4:** Accept the side2 of a triangle into the variable **s2**.

**STEP 5:** Accept the angle of the triangle into the variable **angle**.

**STEP 6:** Calculate **area=s1 * s2 * sin((M_PI / 180) * angle)) / 2**

**STEP 7:** Display area of the Scalene triangle as **area **and return.

` ````
#include<stdio.h>
#include<math.h>
int main() {
int s1, s2, angle;
float area;
printf("\nEnter Side1 : "); /* accepting the side of triangle */
scanf("%d", & s1);
printf("\nEnter Side2 : ");
scanf("%d", & s2);
printf("\nEnter included angle : "); /* accepting angle of triangle */
scanf("%d", & angle );
area = (s1 * s2 * sin((M_PI / 180) * angle)) / 2; /* calculating area using formula */
printf("\nArea of Scalene Triangle : %f", area); /* printing the output */
return (0);
}
```

Enter Side1 : 3 Enter Side2 : 4 Enter included angle : 30 Area of Scalene Triangle : 3.000000