## New Plane and Solid Geometry |

### From inside the book

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**proportional**between the first and last terms , and the last term a third**proportional**to the first and second terms . Thus , in the proportion α = b b C b is a mean**proportional**be- tween a and c , and c a third**proportional**to a ... Page 102

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**proportional**between two numbers is equal to the square root of their product . PROP . II . THEOREM 218. ( Converse of Prop . I. ) If the product of two numbers is equal to the product of two others , one pair may be made the extremes ... Page 104

... ? Ex . 2. If x is a fourth

... ? Ex . 2. If x is a fourth

**proportional**to a , b , c , find x . Ex . 3. Apply composition and division to the following : x + √x2 a2 2a + b x- - √x2- a2 - • 2a - b PROP . VIII . THEOREM 224. In a series of 104 PLANE GEOMETRY - BOOK III. Page 105

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**proportional**to 4 and 12 . Ex . 5. Find a mean**proportional**between 35 and 234 . Ex . 6. If the ratio of the hypotenuse of a right triangle to one of the legs is 2 , the acute angles are 30 ° and 60 ° . Ex . 7. Each of two angles of ... Page 106

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**PROPORTIONAL**LINES 226. Def . Two straight lines are said to be divided propor- tionally when their corresponding ...**proportionally**. Case I. When the segments of each side are commensurable . B E D C Draw A ABC . Take D , a point ...### Other editions - View all

### Common terms and phrases

adjacent angles altitude angle formed angles are equal apothem arc BC base and altitude bisector bisects centre chord circle circumference circumscribed coincide construct Converse of Prop diagonals diameter diedral angle distance Draw line equal parts occur equal respectively equally distant equilateral triangle exterior angle faces frustum Given line given point homologous sides hypotenuse intersecting isosceles trapezoid isosceles triangle lateral area lateral edges line drawn line joining lines be drawn measured by arc middle point number of sides oblique lines opposite parallel parallelogram parallelopiped perimeter perpendicular plane MN polyedron prism Proof proportional Prove pyramid quadrilateral radii radius rectangle regular polygon rhombus right angles right triangle secant segments slant height spherical polygon spherical triangle square straight line surface tangent tetraedron THEOREM trapezoid triedral vertex vertices volume

### Popular passages

Page 168 - S' denote the areas of two © whose radii are R and R', and diameters D and D', respectively. Then, | = "* § = ££ = £• <§337> That is, the areas of two circles are to each other as the squares of their radii, or as the squares of their diameters.

Page 17 - In an isosceles triangle the angles opposite the equal sides are equal.

Page 138 - ... any two parallelograms are to each other as the products of their bases by their altitudes. PROPOSITION V. THEOREM. 403. The area of a triangle is equal to half the product of its base by its altitude.

Page 168 - Similar arcs are to each other as their radii; and similar sectors are to each other as the squares of their radii.

Page 50 - If the diagonals of a quadrilateral bisect each other, the figure is a parallelogram.

Page 128 - In any triangle, the product of any two sides is equal to the product of the segments of the third side formed by the bisector of the opposite angle, plus the square of the bisector.

Page 265 - A spherical polygon is a portion of the surface of a sphere bounded by three or more arcs of great circles. The...

Page 282 - A zone is a portion of the surface of a sphere included between two parallel planes.

Page 241 - Every section of a cylinder made by a plane passing through an element is a parallelogram. Given ABCD, a section of cylinder AC, made by plane through element AB.

Page 256 - A sphere is a solid bounded by a surface all points of which are equally distant from a point within called the centre.