the sides of a triangle are 80 cm, 100cm, and 140 cm. determine the radius of the inscribed circle
1. Draw a sketch.
2. Calculate the area of the triangle: Use Cosine rule to determine one interior angle (i.e. ) of the triangle, for instance the angle opposite the side a. Then the area is:
3. The center of the inscribed circle is the common vertex of three interior triangles whose area is: