The focal distance is 321.9 mm To get this number:
Substitute the base (2a) and rise (b) values in the following elliptical arch formula:
focal distance = sqrt(a² - b²)
focal distance = sqrt((440 mm)² - (300 mm)²)
Perform the corresponding numerical calculations to obtain the focal distance:
focal distance = sqrt(193600 mm² - 90000 mm²)
focal distance = sqrt(103600 mm²)
focal distance = 321.9 mm
That's it! You can always use our arch calculator to test these or other values.
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