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In an isosceles triangle the angles opposite the equal sides are equal.
Elements of Geometry and Trigonometry - Page 20
by Adrien Marie Legendre - 1838 - 269 pages

## Elements of Geometry and Trigonometry: With Notes

Adrien Marie Legendre - Geometry - 1822 - 367 pages
...they are equal. In the same manner it may be shewn, that B is equal to E, and C to F. PROPOSITION XII. THEOREM. In an isosceles triangle, the angles opposite the equal sides are equal. LET the side AB be equal to AC, the angle C will be equal to B. Join A the vertex, and D the middle point of the...

## An Elementary Treatise on Plane and Solid Geometry

Benjamin Peirce - Geometry - 1837 - 216 pages
...respectively eqnnl to those of another, the other sides and angle are also equal in the two triangles. 55. Theorem. In an isosceles triangle the angles opposite the equal sides are equal. Equal Angles of the Isosceles Triangle. Demonstration. In the isosceles triangle ABC (fig. 32), let...

## Elements of Plane Geometry: For the Use of Schools

Nicholas Tillinghast - Geometry, Plane - 1844 - 108 pages
...at C, and DF be equal to AC, EF equal to BC, and the angle at F equal to the angle at C. PROP. VI. THEOREM. In an isosceles triangle, the angles opposite the equal sides are equal. Fig. 6. Let AB, BC, be the equal ! sides ; then we have to prove that the angle A is equal to / i C....

## Elements of Plane Geometry: For the Use of Schools

Nicholas Tillinghast - Geometry, Plane - 1844 - 96 pages
...equal to BC, and the angle at F equal to the angle atC. ' / // / PROP. VI. THEOREM. ./H^'-i-- , &?• In an isosceles triangle, the angles opposite the equal sides are equal. Fig. 6. Let AB, BC, be the equal sides ; then we have to prove that the angle A is equal to C. CDA...

## An Elementary Treatise on Plane and Solid Geometry

Benjamin Peirce - Geometry - 1847 - 150 pages
...respectively equal to those of another, the other sides and angle are also equal in the two triangles. 55. Theorem. In an isosceles triangle the angles opposite the equal sides are equal. Proof. In the isosceles triangle ABC (fig. 32), let the equal sides be AB and BC. Equal Angles of the...

## Elements of Geometry and Trigonometry Translated from the French of A.M ...

Charles Davies - Trigonometry - 1849 - 384 pages
...observed that the equal angles lie opposite the equal sides: thus, the equal angles D and A, lie op posite the equal sides EF and BC. • PROPOSITION XI. THEOREM....triangle, the angles opposite the equal sides are equal. For, join the vertex A, and D the middle point of the base BC. Then, the triangles BAD, DAC, will have...

## Proceedings of the American Association for the Advancement of Science, Volume 8

American Association for the Advancement of Science - Science - 1855 - 396 pages
...the observer at 0', then O' M = his latitude, and PM = 90° ; therefore P D' = • J (90° + lat.). In an isosceles triangle the angles opposite the equal sides are equal ; therefore the angle DPC = DOC, but DOC is the azimuth of the object ; therefore the hour-angle of...

## Elementary Geometry: With Applications in Mensuration

Charles Davies - Geometry - 1850 - 218 pages
...coincide with the parts of the triangle DEF, and therefore, the two triangles are equal, THEOREM VI. In an isosceles triangle the angles opposite the equal sides are equal to each other, C Let ABC be an isosceles triangle, having the side AC equal to the side CB : then will...