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To find the area of a trapezoid. RULE. Multiply half the sum of the two parallel sides by the perpendicular distance between them : the product will be the area.
A System of Geometry and Trigonometry: Together with a Treatise on Surveying ... - Page 33
by Abel Flint - 1804 - 168 pages

## Tables of Logarithms of Numbers and of Sines and Tangents for Every Ten ...

Elias Loomis - Logarithms - 1859 - 372 pages
...one of its sides multiplied by the square root of 3. MENSURATION OF SURFACES. 63 PROBLEM III. (87.) To find the area of a trapezoid. RULE. Multiply half the sum of the parallel sides into their per . pendicular distance. For demonstration, see Geometry, Prop. 7, B. IV....

## A Manual of the Protracting Trigonometer: With Its Application to ...

Josiah Lyman - Electronic book - 1862 - 92 pages
...the field. SECOND METHOD. (S9.) BY TRAPEZOIDS AND TRIANGLES. For a Trapezoid, the rule is, Multiply the sum of the two parallel sides by the perpendicular distance between them. Half the product will be the area. For a Triangle, Multiply the base by the perpendicular height, and...

## Practical Arithmetic: Embracing the Science and Applications of Numbers

Charles Davies - Arithmetic - 1863 - 346 pages
...ABCD, having two of its sides, AB, DC, parallel. The perpendicular, CE, is called, the altitude. 393. To find the area of a trapezoid. Rule. — Multiply half the sum of the two parallel lines by the altitude, and the product will be the area. (Bk. IV., Prop. VII.) Examples. 1. Required...

## Bryant and Stratton's Commercial Arithmetic: In Two Parts : Designed for the ...

Emerson Elbridge White, Henry Beadman Bryant - Bookkeeping - 1865 - 344 pages
...QUADRILATERALS, PENTAGONS, &c. ART. 176- (1.) To find the area of any quadrilateral having two sides parallel. RULE. — Multiply half the sum of the two parallel sides by the altitude, or perpendicular distance between those sides, and the product will be the area. NOTE. —...

## Useful Rules and Tables Relating to Mensuration, Engineering, Structures ...

William John Macquorn Rankine - Engineering - 1866 - 356 pages
...by a pair of parallel straight lines, and a pair of straight lines not parallel). Multiply the half sum of the two parallel sides by the perpendicular distance between them. 3. Triangle. RULE A. — Multiply the length of any one of the sides by one-half of its perpendicular...

## The advanced lesson book, by E.T. Stevens and C. Hole

Edward Thomas Stevens - 1866 - 434 pages
...which has only two of its opposite sides parallel, as ABD c. AE is the perpendicular. c K u To Jind the area of a trapezoid. RULE : — Multiply half the sum of the parallel sides by tho perpendicular distance between them ; the product is the area. DD THE CIRCLE....

## Elements of Plane and Solid Geometry: And of Plane and Spherical ...

Gerardus Beekman Docharty - Geometry - 1867 - 474 pages
...and 25.69 chains respectively, to find the area. Ans. 61 acres, 2 roods nearly. PROBLEM VI. Tojind the area of a trapezoid. RULE. Multiply half the sum of the two parallel sides by the altitude of the trapezoid. (Geom., BI, th. 29.) Or, Multiply the altitude by the distance between the...

## Mensuration for Beginners: With Numerous Examples

Isaac Todhunter - Measurement - 1869 - 312 pages
...Thus we obtain the rule which will now be given. 161. To find the area of a trapezoid. RULE. Multiply the sum of the two parallel sides by the perpendicular distance between them, and half the product will be the area. 162. Examples : (1) The two parallel sides of a trapezoid are...