Elements of Plane Geometry |
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Page 16
... Q.E.D. 66 66 Q.E. F. " hypothesis . quod erat demonstrandum ( which was to be demonstrated ) . quod erat faciendum ( which was to be done ) . PERPENDICULAR AND OBLIQUE STRAIGHT LINES . THEOREM I. 43. At 16 ELEMENTS OF PLANE GEOMETRY ...
... Q.E.D. 66 66 Q.E. F. " hypothesis . quod erat demonstrandum ( which was to be demonstrated ) . quod erat faciendum ( which was to be done ) . PERPENDICULAR AND OBLIQUE STRAIGHT LINES . THEOREM I. 43. At 16 ELEMENTS OF PLANE GEOMETRY ...
Page 18
Franklin Ibach. THEOREM II . 44. The sum of the two adjacent angles ... Q. E.D. 45. COR . 1. - If one of the two adjacent angles formed by two lines ... THEOREM III . 47. CONVERSELY . - If the sum 18 ELEMENTS OF PLANE GEOMETRY .
Franklin Ibach. THEOREM II . 44. The sum of the two adjacent angles ... Q. E.D. 45. COR . 1. - If one of the two adjacent angles formed by two lines ... THEOREM III . 47. CONVERSELY . - If the sum 18 ELEMENTS OF PLANE GEOMETRY .
Page 19
... . ( Ax . 1 ) From each member subtract a . Then △ b = △ ACD , which is impossible . ( Ax . 8 ) .. AC and BC lie in the same straight line . Q. E. D. THEOREM IV . 48. If two straight lines intersect , ELEMENTS OF PLANE GEOMETRY . 19.
... . ( Ax . 1 ) From each member subtract a . Then △ b = △ ACD , which is impossible . ( Ax . 8 ) .. AC and BC lie in the same straight line . Q. E. D. THEOREM IV . 48. If two straight lines intersect , ELEMENTS OF PLANE GEOMETRY . 19.
Page 20
... Q. E. D. 49. COR . 1. - If two straight lines intersect , the sum of the four angles formed equals four right angles . 50. COR . 2. — The sum of all the angles that can be formed at a common point equals four right angles . THEOREM V ...
... Q. E. D. 49. COR . 1. - If two straight lines intersect , the sum of the four angles formed equals four right angles . 50. COR . 2. — The sum of all the angles that can be formed at a common point equals four right angles . THEOREM V ...
Page 21
... equal . Then PD is L to AB . ( 20 ) There is only one position of the line in which the angles are equal . ... only one can be drawn from P to AB . Q. E. D. THEOREM VI . 52. From a point without a straight ELEMENTS OF PLANE GEOMETRY . 27 ...
... equal . Then PD is L to AB . ( 20 ) There is only one position of the line in which the angles are equal . ... only one can be drawn from P to AB . Q. E. D. THEOREM VI . 52. From a point without a straight ELEMENTS OF PLANE GEOMETRY . 27 ...
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Common terms and phrases
AB² ABC and DEF AC and BC acute angle adjacent angles angles are equal angles equals angles formed arc AC BC² bisectors bisects centre CF meet chord common point Concave Polygon construct Convex Polygon COR.-The decagon DEF are similar diagonal BC diameter Draw the diagonal equally distant equals two right equiangular Equilateral Polygon exterior angles given circle given straight line homologous sides hypothenuse included angle intersect La=Lb Let ABCD line joining lines drawn measured by arc medial lines middle point oblique lines parallelogram perimeter PLANE GEOMETRY produced proportion Q. E. D. THEOREM Q. E. F. PROBLEM quadrilateral radii radius rectangle regular inscribed regular polygon respectively equal rhombus right angles right-angled triangle SCHOLIUM secant similar polygons square Subtract tangent third side trapezoid triangles are equal vertex vertical angle
Popular passages
Page 14 - Things which are equal to the same thing, are equal to each other. 2. If equals are added to equals, the sums are equal. 3. If equals are subtracted from equals, the remainders are equal. 4. If equals are added to unequals, the sums are unequal.
Page 83 - In a series of equal ratios, the sum of the antecedents is to the sum of the consequents as any antecedent is to its consequent.
Page 85 - CIRCLE is a plane figure bounded by a curved line, all the points of which are equally distant from a point within called the centre; as the figure ADB E.
Page 44 - If two triangles have two sides of the one respectively equal to two sides of the other, and the included angles unequal, the triangle which has the greater included angle has the greater third side.
Page 14 - Axioms. 1. Things which are equal to the same thing are equal to each other. 2. If equals are added to equals, the wholes are equal. 3. If equals are taken from equals, the remainders are equal.
Page 136 - In any triangle, the square of the side opposite an acute angle is equal to the sum of the squares of the other two sides, minus twice the product of one of these sides and the projection of the other side upon it.
Page 123 - Upon a given straight line to describe a segment of a circle, which shall contain an angle equal to a given rectilineal angle.
Page 55 - A polygon of three sides is a triangle ; of four, a quadrilateral; of five, a pentagon ; of six, a hexagon ; of seven, a heptagon; of eight, an octagon; of nine, a nonagon; of ten, a decagon; of twelve, a dodecagon.
Page 137 - In any triangle the square of the side opposite an acute angle is equal to the sum of the squares of the other two sides diminished by twice the product of one of those sides and the projection of the other upon that side.
Page 177 - From this proposition it is evident, that the square described on the difference of two lines is equivalent to the sum of the squares described on the lines respectively, minus twice the rectangle contained by the lines.