PROBLEM XII. To divide a given Triangle ABC, into two equal parts. B C A D Bifect one of the fides in D. Draw a line from D, to the oppofite angle, which will divide the triangle into two equal parts. PROBLEM XIII. To defcribe a Square, upon a given line AB. Raife a perpendicular, at one end of the given line. arc. With the fame radius, and A as a centre, defcribe another arc croffing the first in D. Draw the lines DC, DA, which will complete the Square required. PROBLEM XIV. To defcribe a Rectangle, whofe length and breadth fhall be equal to two given lines, AB Raise a perpendicular at one end of the longest line, as at B. Make the perpendicular B D, equal to the shortest line C. arc. With the radius A B, and D as a centre, defcribe an With the radius C, and A as a centre, defcribe another arc croffing the first in E. Draw the lines DE and AE, which will complete the Rectangle required.. Draw C any chord A B, and bifect it' at right angles with the perpendicular CD. Bifect C D in E, which will be the centre of the circle required. PROBLEM XVI: Through three given points A, B and C, to deScribe the circumference of a Circle. Draw two right lines A B and B C, joining the points A B and B C. Bifect these two lines with two others drawn at right angles to them, and produce them till they meet in the point D. With the radius D B, or DC, or D A, and D as a centre, describe a circle which will pafs through the points required. |