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 121
... 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 122
... 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 123
... 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 tó 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 tó EA . Therefore , as BD to DA , so is CE to EA ...
Page 132
... altitude , AB : FE :: DB : BE ( 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 . But ...
... altitude , AB : FE :: DB : BE ( 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 . But ...
Page 141
... 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 base BC bisected centre chord circle ABC circumference cosine cylinder demonstrated described diameter divided draw equal and similar equal angles equiangular equilateral equilateral polygon equimultiples Euclid exterior angle fore four right angles given rectilineal given straight line greater Hence hypotenuse inscribed join less Let ABC magnitudes meet multiple opposite angle parallel parallelogram parallelopiped perpendicular plane polygon prism PROB PROP proportional proposition quadrilateral radius ratio rectangle contained rectilineal figure remaining angle right angled triangle 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 49 - 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 of the line between the points of section, is equal to the square of half the line.
Page 147 - ... cuts the base, the rectangle contained by the sides of the triangle is equal to the rectangle contained by the segments of the base, together with the square on the straight line which bisects the angle.
Page 292 - 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 7 - 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 139 - K hag to M the ratio which is compounded of the ratios of the sides ; therefore also the parallelogram AC has to the parallelogram CF the ratio which is compounded of the ratios of the sides. COR. Hence, any two rectangles are to each other as the products of their bases multiplied by their altitudes.
Page 33 - Parallelograms upon the same base and between the same parallels, are equal to one another.
Page 79 - If a straight line touch a circle, and from the point of contact a straight line be drawn cutting the circle, the angles made by...
Page 125 - If two triangles have one angle of the one equal to one angle of the other and the sides about these equal angles proportional, the triangles are similar.
Page 131 - If four straight lines be proportionals, the rectangle contained by the extremes is equal to the rectangle contained by the means; And if the rectangle contained by the extremes be equal to the rectangle contained by the means, the four straight lines are proportionals. Let the four straight lines, AB, CD, E, F, be proportionals, viz.
Page 78 - 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.