## The Elements of Euclid: Viz. the First Six Books, Together with the Eleventh and Twelfth |

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Page 4

Quadrilateral , by

Quadrilateral , by

**four**straight lines . XXIII . Multilateral figures , or polygons , by more than**four**straight lines . XXIV . Of three - sided figures , an equilateral triangle is that which has three equal sides XXV . Page 5

Of

Of

**four**- sided figures , a square is that which has all its sides equal , and all its angles right anglese XXXI . An oblong is that which has all its angles right angles , but has not all its sides equal . XXXII . Page 20

I. From this it is manifest , that , if two straight lines cut one another , the angles which they make at the point where they cut , are together equal to

I. From this it is manifest , that , if two straight lines cut one another , the angles which they make at the point where they cut , are together equal to

**four**right angles . Cor . 2. And consequently that all the angles made by any ... Page 34

Therefore all the angles of the figure , together with

Therefore all the angles of the figure , together with

**four**right angles , are equal to twice as many right angles as the figure has sides . Cor . 2. - All the exterior angles of any rectili . neal figure are together equal to**four**... Page 35

... that is , by the foregoing corollary , they are equal to all the interior angles of the figure , together with

... that is , by the foregoing corollary , they are equal to all the interior angles of the figure , together with

**four**right angles ; therefore all the exterior angles are equal to**four**right angles . PROP . XXXIII . THEOR .### What people are saying - Write a review

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The Elements of Euclid: Viz. The First Six Books, Together With the Eleventh ... Euclid Euclid No preview available - 2018 |

### Common terms and phrases

altitude angle ABC angle BAC base base BC BC is equal centre circle ABCD circumference common cone Const contained cylinder demonstrated described diameter divided double draw drawn equal angles equiangular equilateral equimultiples extremities fall figure fore four fourth given given straight line greater half inscribed join less Let ABC likewise magnitudes manner meet multiple opposite parallel parallelogram pass perpendicular plane polygon prism PROB produced PROP proportionals proved pyramid ratio reason rectangle contained rectilineal figure remaining angle right angles segment shown sides similar solid solid angle solid parallelopiped sphere square taken THEOR third touches triangle ABC vertex wherefore whole