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Containing an Explanation of the three Varieties of right angled
Triangles, and the four Cases of Oblique, together with a
By RICHARD COCKREL,
Teacher of the Free School, at LARTINGTON.
? Perveniri ad summa, nisi ex principiis, non
Printed and sold by M. HEAVISIDES, for the Author; by Messrs.
Law and Son, Ave Maria Lane; and Mr. D. TAYLOR,
+ signifies Addition, so 2 + 4 means that
2 and 4 are to be added together.
that 2 is to be taken from 4. = denotes Equality, so 4 = 3+1 signifies
that 4 is equal 3 when added to 1.
2 signifies any Angle.
HE Number of Publications already ex
tant, treating on TRIGONOMETRY, well persuaded occupy no inconsiderable Part of the Bookseller's Shelves. But as Improvement does not always keep Pace with the Time and Labor bestowed on a Subje£t, so the Treatises already abroad on this Science, do not exclude any Necesity for further Elucidation.
The two following substantial Reasons, are what I lay before the Public as an Apology for sending this Work abroad into the World.
I. That the Books for the most part which contain any Thing of Plain Trigonometry, are Books, which treat of one or more of the other mathematical Sciences, as Mensuration, Navigation, Astronomy, &c. and thereby the Price of the Books becomes 5, 6 or perhaps 75. 6d. Purchase. Now I have by treating of this Branch singly, reduced the Purchase, several Shillingsman Obje£t you know to those in poor Circumsances! And II. The Way in which I have treated this Subject, is entirely new,
I mean as to the Plan. And as far as I fee,