5 most overlooked points while solving GMAT triangle based problems (under Geometry)

1. Similar triangles are triangles whose sides are proportional. If ABC and PQR are two similar triangles then AB/PQ = BC/QR =AC/PR. The angles opposite to the sides(which are in a ratio) are also proportional  
   
2.   Area of a triangle(sides are a,b,c) is based on the hero’s formula 

           

          s= (a+b+c)/2 , R = circum radius and r= inradius

  3.   The sum of two sides of a triangle is greater than or equal to the third side and the difference of any    

      two sides is lesser than or equal to the third side. This property is used extensively in GMAT higher

           difficult problems

    4.    For the equilateral and the isosceles triangle the altitude bisects the base and hence the triangle into
           two equal parts

    5.    The largest triangle (with the maximum area) which can be inscribed in a circle is the equilateral
           triangle.