Oracle: How to determine total memory assigned for SGA and PGA

By using SQLPlus or TCODE: DBACOCKPIT to determine the total memory assigned for System Global Area (SGA) and Program Global Area (PGA)

Steps for SGA:

Option 1: By using SQLPlus, 

Execute SQL Command: show sga (sample show ~4GB for SGA)

Option 2: TCODE: DBACOCKPIT

Tcode: DBACOCKPIT -> Performance -> Statistical information -> SGA Monitor -> SGA tab

Steps for PGA:

Tcode: DBACOCKPIT -> Performance -> Statistical information -> PGA Monitor -> PGA Status tab (Parameter: Total PGA allocated)