Draw a line joining vertex #C# and vertex #D#, as shown in the figure.
In #DeltaCDH, anglef+angleg+angleh=180^@#
In #DeltaBEH, angleb+anglee+angleh=180^@#
#=> angleb+anglee=anglef+angleg#
In #DeltaACD, anglea+anglec+angled+anglef+angleg=180^@#
#=> anglea+anglec+angled+angleb+anglee=180^@#
Sol. 2) See Fig 2
In #DeltaACG, angleAGC=180-(anglea+anglec)#
#=> angleFGE=anglea+anglec#
In #DeltaBDF, angleBFD=180-(angleb+angled)#
#=> angleGFE=angleb+angled#
In #DeltaEFG, anglea+angleb+anglec+angled+anglee=180^@#
Hnece, the sum of the five interior angles in a 5-point star
#= anglea+angleb+anglec+angled+anglee=180^@#