Find the area the figure is not drawn to scale 6.9 cm 4 cm

Please check attached file to see if you mean the same triangle. 

Basically, to find the area of a triangle, you are going to use the formula :
 A = b × h        where b is base, h is height.
          2

others also use the formula:  Area=1/2(bxh)

Based on the figure, we have 6.9 cm (base) and 4 cm (height) as given.
Let us work out on the area of the said triangle.
A= 6.9cm × 4cm
             2

  = 27.6cm²
       2
A= 13.8 cm²

Hope this helps!
   

The third box is a function