# Area of a Triangle using Radius and Perimeter

Area of a triangle can be calculated using its perimeter and the radius of the circle which is inscribed in the triangle.

### Worked Examples of Area of a Triangle using Radius and Perimeter

(a)    Find an expression for the area of $\triangle LOM$.

(b)    Show that the area of $\triangle KLM$ is given by $\displaystyle A = \frac{1}{2} Tr$, where $T$ is the perimeter of $\triangle KLM$.

(c)    Find how far from the foot of the fence the board touches the ground.

(d)    Find the radius of the second circle.