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The Analogie or Proportion is,
As the Radius is to the Co-sine of the Hypotenuse A B 60 deg. So is the Tangent of the Angle at the Base A 23 degr. 30 min. to the Co-tangent of the Angle at the Perpendicular B.
FIrst, draw a right Line, as C H, and upon one end there∣of (as at C) erect the Perpendicular C A, and with the distance of 60 degr. of your Line of Chords, upon the Cen∣tre C describe the Quadrant C A D. Also upon the Point A with 60 degr. of your Chord describe the Quadrant A B C.
Being thus prepared, First, take 60 deg. the Co-sine of the Hypotenuse A B, and set them from A to O; also take 23 d. 30 m. the quan∣tity of the An∣gle at A, and set them from C to r; and draw the Line A M F, and the Line O G, parallel to A C.
Then take in your Compasses the distance be∣tween C and G, and setting one foot in D, with the other de∣scribe the Arch K, and draw the Line A L so that it onely touch the Arch K. Then placing one foot of the Compasses in F, take the least distance you can to the Line C L, which set from C to E. Lastly, draw the Line A E, cutting the Quadrant C B in N. So the distance
C N measured upon your Chords shall give you 20 degr. 38 min. the Complement of the Angle at B, which was re∣quired; or, the distance B N will give you 69 degr. 22 min. the Angle it self.