Let us check whether the point P ( 10 , 15 ) lies inside the triangle formed by A ( 0 , 0 ) , B ( 20 , 0 ) and C ( 10 , 30 )
if ( isInside ( 0 , 0 , 20 , 0 , 10 , 30 , 10 , 15 ) ) document . write ( " " ) ; else document . write ( " " ) ;