The mariners magazine, or, Sturmy's mathematical and practical arts containing the description and use of the scale of scales, it being a mathematical ruler, that resolves most mathematical conclusions, and likewise the making and use of the crostaff, quadrant, and the quadrat, nocturnals, and other most useful instruments for all artists and navigators : the art of navigation, resolved geometrically, instrumentally, and by calculation, and by that late excellent invention of logarithms, in the three principal kinds of sailing : with new tables of the longitude and latitude of the most eminent places ... : together with a discourse of the practick part of navigation ..., a new way of surveying land ..., the art of gauging all sorts of vessels ..., the art of dialling by a gnomical scale ... : whereunto is annexed, an abridgment of the penalties and forfeitures, by acts of parliaments appointed, relating to the customs and navigation : also a compendium of fortification, both geometrically and instrumentally / by Capt. Samuel Sturmy.

PROBL. XIX. How to divide a Triangle (whose Area or Content is known) into two Parts, by a Line drawn from an Angle assigned, according to any Proportion required.

LEt the Triangle ABC contain 9 Acres, and let it be required to divide the same into two Parts, by a Line drawn from the Angle A, the one to contain 5 Acres, and the other 4 Acres. First, measure the whole length of the Base, which suppose 45; Then say, If 9 Acres the quantity of the whole Triangle, give 45 the whole Base, What parts of the Base shall 4 Acres give? Multiply and divide, the Quotient

will be 20 for the lesser Segment of the Base BD; which being deducted from 45 the whole Base DC, then draw the Line AD, which shall divide the Triangle ABC according to the proportion required.

If 9 Acres give 45, What shall 4 Acres give?

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