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The area of a circle is equal to one-half the product of its circumference and radius.
A Grammar Shcool Arithmetic - Page 320
by George Albert Wentworth - 1886 - 372 pages

## Elements of Plane and Solid Geometry

George Albert Wentworth - Geometry - 1877 - 426 pages
...to the perimeter of the polygon. .'. the area of the polygon = £ RX P. PROPOSITION X. THEOREM. 380. The area of a circle is equal to one-half the product of its .radius by its circumference. Let R represent the radius, and С the circumference of a circle....

## Elements of Geometry

George Albert Wentworth - 1881 - 266 pages
...the perimeter of the polygon. .-. the area of the polygon = £ RX P. QED PROPOSITION X. THEOREM. 380. The area of a circle is equal to one-half the product of its radius by its circumference. Let R represent the radius, and С the circumference oí a circle....

## A Treatise on Special Or Elementary Geometry

Edward Olney - Geometry - 1882 - 262 pages
...the fact. It is especially worthy of note in the case of a triangle. See Kg. 60. PROPOSITION IX. 328. Theorem. — The area of a circle is equal to one-half the product of its radius into its circumference. DKM. — Let Oa be the radius of a circle. Circumscribe any regular...

## Elementary Geometry: Including Plane, Solid, and Spherical Geometry, with ...

Edward Olney - Geometry - 1883 - 354 pages
...circumference of the circle as its limit, since the circle is the limit of such a polygon. PROPOSITION XI. 356. Theorem. — The area of a circle is equal to onehalf the product of its radius into its circumference. DEMONSTRATION. Let O<f (Fig. 179) be the radius of the circle. Fig....

## The Elements of Geometry

Webster Wells - Geometry - 1886 - 392 pages
...Two similar sectors are to each other as the squares of their radii. PROPOSITION XV. THEOREM. 396. The area of a circle is equal to one-half the product of its circumference and radius. (Compare §^322.) Let B and K denote the radii, C and^_the_circB Let...

## Manual of Plane Geometry: On the Heuristic Plan, with Numerous Extra ...

George Irving Hopkins - 1891 - 208 pages
...the squares of the radii, and also of the diameters, of the circles of which they are a part. 524. The area of a circle is equal to one-half the product of its circumference and radius. Sug. Consult 498 and 510. 525. The area of a sector is equal to one-half...

## Report, Volume 10

Oregon. Office of Superintendent of Public Instruction - Education - 1893 - 266 pages
...many times, less two, as the figure has sides. 8. To circumscribe a circle about a given triangle. 9. The area of a circle is equal to one-half the product of its radius by its circumference. 10. In any triangle the square of the side opposite an acute angle...

## Mensuration

William Shaffer Hall - Measurement - 1893 - 62 pages
...circle is equal to IT, multiplied by the square of the radius. For Proof: See Ww. Geom., 381. EULE II: The area of a circle is equal to one-half the product of its radius by its circumference. For Proof: See Ww. Geom., 380. § 35". To find the radius of a circle...