A complete and practical solution book for the common school teacher (1899)
Fairchild, J[ohn] T[heodore] [from old catalog] · Crawfis College, Ohio, The author · leaf 180
65.64 sq. ft. PROBLEM 349.At 80 cents a rod, what would be the cost of fencing- a field in theform of an equilateral triangle, its altitude being 6 rd.? Solution. (1) Let ABC be the triangle. (2) AO bisects the angle A, then angle OAD=30°. Then AODis a right-angled triangle. (3) Now, OD+DE = CO, or… … PIG. 40. NoTK.—As AOD is a right triangle and the angle OAD=30°, thenAO=4 and OD=2 rd. It follows that the hjpothenuse is twice the sideopposite the acute angle of a right triangle which is 30°. Also if thehjpothenuse be given, then the side opposite the 30° angle is half ofthe hypothenuse. Prove…
Arithmetic · Geometry
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