Sentence:  If | a is the multiple secant of \ g which passes through * * f and | b is the simple secant of \ g which passes through * * f , and if * * f are the points in which | a meets \ g , and if * * f <WSD>is</WSD> the image of * * f on the generator | b , it follows that the image of the line * * f is * * f . 
Meaning of the word marked with <WSD> tags:  be identical to; be someone or something