Need Help to Calculate True Involute Form Dia of an Internal Metric Involute Gear

Hi,

Please suggest me how to calculate True Involute Form Dia of an Internal Metric Involute Gear.
I know how to calculate the same for external gear but I'm not able to do the same for Internal Gear.
Please reply fast.

See the following webpages:

[URL="http://www.engineersedge.com/gears/spline_engineering_design_formula_13153.htm"][B]Spline Engineering Design Formula[/B][/URL]

[URL="http://www.engineersedge.com/gears/gear_specifications_on_engineering_drawings_13152.htm"][B]Gear Specifications on Engineering Drawings[/B][/URL]

[URL="http://www.engineersedge.com/gears/splined_gears_preferred_number_of_teeth_6mm_to_58mm_13150.htm"][B]Splined Gears Preferred Number of Teeth 6mm to 58mm[/B][/URL]

[URL="http://www.engineersedge.com/gears/splined_gears_preferred_number_of_teeth_60mm_to_500mm_13148.htm"][B]Splined Gears Preferred Number of Teeth 60mm to 500mm[/B][/URL]