## Elements of Geometry and Trigonometry |

### From inside the book

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**middle**. Angles , like all other quantities , are susceptible of addition , subtraction , multiplication , and division . Thus the angle DCE is the sum of the two angles DCB , BCE ; and the an- gle DCB is the difference of the two ... Page 20

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**middle**point of the base BC . Then , the triangles BAD , DAC , will have all the sides of the one equal to those of the other , each to each ; for BA is equal to AC , by hypothesis ; AD is common , and BD is equal to DC by construction ... Page 23

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**middle**point of a straight line , a perpendicular be drawn to this line ; 1st , Every point of the perpendicular will be equally distant from the extremities of the line . 2d , Every point , without the perpendicular , will be unequally ... Page 24

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**middle**point , and ECF the perpendicular . First , Since AC = CB , the two oblique lines AD , DB , are equally distant from the perpen- dicular , and therefore equal ( Prop . XV . ) . So , likewise , are the two oblique lines AE , EB ... Page 25

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**middle**point of BA , draw the straight line EGF , perpendicular to EC . It will also be perpendicular to BD . For , the sum BAC + ABD is equal to two right angles , by hypothesis ; the sum BAC + BAE is likewise equal to two right angles ...### Other editions - View all

### Common terms and phrases

adjacent adjacent angles altitude angle ACB angle BAC ar.-comp base multiplied bisect Book centre chord circ circumference circumscribed common cone convex surface Cosine Cotang cylinder diagonal diameter dicular distance draw drawn equal angles equally distant equiangular equivalent figure formed four right angles frustum given angle given line gles greater homologous sides hypothenuse inscribed polygon intersection less Let ABC let fall logarithm measured by half number of sides oblique lines opposite parallelogram parallelopipedon pendicular perimeter perpen perpendicular plane MN polyedron polygon ABCDE prism proportional PROPOSITION pyramid quadrant quadrilateral quantities radii radius ratio rectangle regular polygon right angled triangle S-ABC Scholium secant secant line segment side BC similar sine solid angle solid described sphere spherical polygon spherical triangle square described straight line tang tangent THEOREM triangle ABC triangular prism vertex