THerefore, if the Radius of the side of the Hexagon is a the side of the Decagon will be 〈 math 〉〈 math 〉, by Schol. 2. Prop. 27. e. g. if the Radius be 10, the side of the Decagon will be 〈 math 〉〈 math 〉, and if the Radius be put 10000000, the side of the Decagon will be = 〈 math 〉〈 math 〉, viz. by adding the Square of the Radius and the Square of half the Radius into one Sum; whence you'l have the side of the Decagon =6180340; the half whereof 3090170 gives the difference between the Perpendiculars of the Triangle and the Pentagon, by Cons. 3. Prop. 51.
II. The side therefore of the Pentagon is by Prop. 〈 math 〉〈 math 〉; for the Square of the Hexagon is aa or 〈 math 〉〈 math 〉 aa, the □ of the Decagon 〈 math 〉〈 math 〉: the Root extracted out of the Sum of these is the side of the Pentagon, viz. 〈 math 〉〈 math 〉 e. g. if the Radius be 10, the side of the Pentagon will be 〈 math 〉〈 math 〉, and if the Radius be put 10000000, since the side of the Hexagon is equal to it, and the side of the Decagon 6180340, their Squares being added into one Sum, the Root extracted out of that Sum will give the side of the Pentagon, 1755704 nearly; and the sides being collected into