Elements of Geometry: Containing the First Six Books of Euclid, with a Supplement on the Quadrature of the Circle, and the Geometry of Solids: to which are Added, Elements of Plane and Spherical Trigonometry |
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Page 115
... altitude of a triangle is the straight line drawn from its vertex perpendicular to the base . The altitude of a parallelogram is the perpendicu- lar which measures the distance of two oppo- site sides , taken as bases . And the altitude ...
... altitude of a triangle is the straight line drawn from its vertex perpendicular to the base . The altitude of a parallelogram is the perpendicu- lar which measures the distance of two oppo- site sides , taken as bases . And the altitude ...
Page 116
... altitudes , are to one another as their bases . Let the figures be placed so as to have their bases in the same straight line ; and having drawn perpendiculars from the vertices of the triangles to the bases , the straight line which ...
... altitudes , are to one another as their bases . Let the figures be placed so as to have their bases in the same straight line ; and having drawn perpendiculars from the vertices of the triangles to the bases , the straight line which ...
Page 117
... altitude , viz . the perpendicular drawn from the point E to AB , they are to one another as their bases ; and for the same reason , as the triangle CDE to the triangle ADE , so is CE to EA . Therefore , as BD to DA , so is CE to EA ...
... altitude , viz . the perpendicular drawn from the point E to AB , they are to one another as their bases ; and for the same reason , as the triangle CDE to the triangle ADE , so is CE to EA . Therefore , as BD to DA , so is CE to EA ...
Page 126
... altitude , AB : FE : : DB : P.E ( 1. 6. ) , also , BC : FE :: GB : BF ( 1. 6. ) ; therefore DB : BE :: GB : BF ( 11.5 . ) . Wherefore , the sides of the parallelograms AB , BC about their equal angles are reciprocally pro- portional ...
... altitude , AB : FE : : DB : P.E ( 1. 6. ) , also , BC : FE :: GB : BF ( 1. 6. ) ; therefore DB : BE :: GB : BF ( 11.5 . ) . Wherefore , the sides of the parallelograms AB , BC about their equal angles are reciprocally pro- portional ...
Page 135
... altitudes . SCHOLIUM . Hence the product of the base by the altitude may be assumed as the measure of a rectangle , provided we understand by this product the pro- duct of two numbers , one of which is the number of linear units ...
... altitudes . SCHOLIUM . Hence the product of the base by the altitude may be assumed as the measure of a rectangle , provided we understand by this product the pro- duct of two numbers , one of which is the number of linear units ...
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Common terms and phrases
ABC is equal ABCD adjacent angles altitude angle ABC angle ACB angle BAC angles equal arc AC base BC bisected centre chord circle ABC circumference cosine cylinder demonstrated diameter divided draw Prob equal and similar equal angles equiangular equilateral equilateral polygon equimultiples Euclid exterior angle fore four right angles given straight line greater Hence hypotenuse inscribed join less Let ABC Let the straight magnitudes meet multiple opposite angle parallel parallelogram parallelopiped perpendicular plane polygon prism PROP proposition quadrilateral radius ratio rectangle contained rectilineal figure remaining angle SCHOLIUM segment semicircle shewn side BC sine solid angle solid parallelopiped spherical angle spherical triangle square straight line BC THEOR third touches the circle triangle ABC triangle DEF wherefore
Popular passages
Page 46 - If a straight line be divided into any two parts, the square of the whole line is equal to the squares of the two parts, together with twice the rectangle contained by the parts.
Page 39 - To describe a parallelogram that shall be equal to a given triangle, and have one of its angles equal to a given rectilineal angle.
Page 47 - If a straight line be divided into two equal parts, and also into two unequal parts, the rectangle contained by the unequal parts, together with the square on the line between the points of section, is equal to the square on half the line.
Page 25 - THE straight lines which join the extremities of two equal and parallel straight lines, towards the same parts, are also themselves equal and parallel. Let AB, CD be equal and parallel straight lines, and joined towards the same parts by the straight lines AC, BD ; AC, BD are also equal and parallel.
Page 5 - A circle is a plane figure contained by one line, which is called the circumference, and is such that all straight lines drawn from a certain point within the figure to the circumference, are equal to one another.
Page 75 - The angle in a semicircle is a right angle; the angle in a segment greater than a semicircle is less than a right angle; and the angle in a segment less than a semicircle is greater than a right angle.
Page 95 - If two triangles have two angles of the one equal to two angles of the other, each to each, and one side equal to one side, viz. either the sides adjacent to the equal...
Page 294 - All the interior angles of any rectilineal figure, together with four right angles, are equal to twice as many right angles as the figure has sides.
Page 52 - In obtuse-angled triangles, if a perpendicular be drawn from either of the acute angles to the opposite side produced, the square of the side subtending the obtuse angle, is greater than the squares of the sides containing the obtuse angle, by twice the rectangle contained by the side upon which, when produced, the perpendicular falls, and the straight line intercepted without the triangle, between the perpendicular and the obtuse angle. Let ABC be an obtuse-angled triangle, having the obtuse angle...
Page 134 - Equiangular parallelograms have to one another the ratio which is compounded of the ratios of their sides.