1. Denomination. Make AB=a, BD=b, AC=x; then will BC=x+b.
2. Equation by the Pythagorick Theorem, 〈 math 〉〈 math 〉, viz. the two Squares of the Sides to the Square of the Hypothenusa.
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1. Denomination. Make AB=a, BD=b, AC=x; then will BC=x+b.
2. Equation by the Pythagorick Theorem, 〈 math 〉〈 math 〉, viz. the two Squares of the Sides to the Square of the Hypothenusa.
3. Reduction. Substracting from both sides xx, you'l have 〈 math 〉〈 math 〉; and moreover by substracting also 〈 math 〉〈 math 〉; and dividing by 〈 math 〉〈 math 〉.
4. Effection or Geometrical Construction. Having described upon the given Base AB a Semi-circle, apply therein the given difference BD, and draw AD, whose Square is =aa−bb. Since this must be divided by 2b, make, as AE=2b to AD = 〈 math 〉〈 math 〉, so AD = 〈 math 〉〈 math 〉 to AC the Per∣pendicular sought. To which if you add CF=BD, you will have AF= to the Hypothenusa sought BC; which will come of course together with the whole Triangle sought, if the found Perpendicular AC be erected at right Angles on the given Base AB.
5. The Rule for Arithmetical Cases. From the square of the given Base substract the square of the given difference, and divide the Remainder by the double difference; and you'l have the Perpendicular sought. E. g. suppose the Base = 20 foot, and the difference between the Perpendicular and Hypothenu∣sa 10.