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In an isosceles triangle the angles opposite the equal sides are equal.
Elements of Plane and Solid Geometry - Page 46
by George Albert Wentworth - 1877 - 398 pages

## Syllabus of Propositions in Geometry: Intended for Use in Preparing Students ...

Harvard University - Geometry - 1899 - 39 pages
...respectively equal to a side and the two adjacent angles of the other, the triangles are equal. THEOREM III. In an isosceles triangle the angles opposite the equal sides are equal „ Conversely, if two angles of a triangle are equal, the triangle is isosceles. THEOREM IV. If two...

## Plane Geometry

William James Milne - Geometry, Modern - 1899 - 258 pages
...the «qual sides compare in size ? 2. How do the angles of an equilateral triangle .compare? Theorem. In an isosceles triangle the angles opposite the equal sides are equal. Data : Any isosceles triangle, as ABC, in which C = BC. To prove angle A = angle B. Proof. Draw CD...

## Grammar School Arithmetic

Adelia Roberts Hornbrook - Arithmetic - 1900 - 428 pages
...isosceles triangle so that the equal sides coincide. Can you see that the following statement is true ? In an isosceles triangle the angles opposite the equal sides are equal. 352. How many degrees are there in each angle of the isosceles triangle ABC? Explain. 353. How many...

## A Textbook on Mining Engineering, Volume 1

1900 - 732 pages
...the base, or to the base extended. Thus, in Figs. 33 and 34, BD is the altitude of the triangles ABC. In an isosceles triangle, the angles opposite the equal sides are equal. Thus, in Fig. 35, AB = BC; hence, angle C — angle A. In any isosceles triangle, if a perpendicular...

## A Treatise on Coal Mining: Prepared for Students of the International ...

International Correspondence Schools - Coal mines and mining - 1900 - 712 pages
...base, or to the base extended. Thus, in Figs. 33 and altitude in BD is the _ of the triangles ABC. . In an isosceles triangle, the angles opposite the equal sides are equal. Thus, in Fig. 35, AB — BC; hence, angle C = angle A. In any isosceles triangle, if a perpendicular...

## Elements of Plane Geometry

Alan Sanders - Geometry, Modern - 1901 - 260 pages
...of the other pair of vertical angles. Find the values of the four angles. PROPOSITION X. THEOREM 81. In an isosceles triangle, the angles opposite the equal sides are equal. Let ABC be an isosceles A, having AB = BC. To Prove Z A = Z C. Proof. Draw BD bisecting AC. (§ 55.) B...

## Plane Geometry

Edward Brooks - 1901 - 278 pages
...triangles coincide in all their parts and are equal. Therefore, etc. PROPOSITION XXI. — THEOREM. In an isosceles triangle the angles opposite the equal sides are equal. Given. — Let ABC be an isosceles triangle having the side AC equal to the side BC. To Prove. —...

## Non-Euclidean Geometry

Henry Parker Manning - Geometry, Non-Euclidean - 1901 - 116 pages
...the included anyle, of one equal, respectively, to the corresponding parts of the other. 4. Theorem. In an isosceles triangle the angles opposite the equal sides are equal. Bisect the angle at the vertex and use (3). 5. Theorem. The perpendiculars erected at the middle points...