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For the same reason, CD is likewise at right angles to the plane HGK. Therefore AB, CD are each of them at right angles to the plane HGK.
An elementary course of mathematics - Page 13
by Samuel Hunter Christie - 1847

## Euclid's Elements of geometry [book 1-6, 11,12] with explanatory notes ...

Euclides - 1845 - 546 pages
...them : (xi. 4.) and EF is parallel to AB therefore AB is at right angles to the plane HGK. (xi. 8.) For the same reason, CD is likewise at right angles...to the same plane, they are parallel to one another : (xi. 6.) therefore AB is parallel to CD. Wherefore, two straight lines, &c. QED PROPOSITION X. THEOREM....

## Euclid in Paragraphs: The Elements of Euclid: Containing the First Six Books ...

Euclid - Geometry - 1845 - 218 pages
...through them: and t s. 11. EF is parallel to AB ; therefore AB is at right angles f to the plane HGK : For the same reason, CD is likewise at right angles...plane HGK. But if two straight lines are at right i <;. 11. angles to the same plane, they shall be parallelJ to one another; therefore AB is parallel...

## The First Six, and the Eleventh and Twelfth Books of Euclid's Elements: With ...

Euclides, James Thomson - Geometry - 1845 - 382 pages
...sam« plane. Therefore, if three straight lines, eSzc. PROP. VI. THEOR. — If two straight lines be at right angles to the same plane, they are parallel to one another. Let the straight lines AB, CD be at right angles to the same plane BDE ; AB is parallel to CD. Let...

## Elements of Geometry: Containing the First Six Books of Euclid, with a ...

Euclid, John Playfair - Euclid's Elements - 1846 - 334 pages
...and EF is parallel to AB ; therefore AB is at right angles (7. 2. Sup.) to the plane — — .° HGK. For the same reason, CD is likewise at right angles to the plane HGK. Therefore AB, CD _ \ •_ are each of them at right angles / ^ to the plane HGK. But if two / straight lines are at...

## Elements of Geometry: Containing the First Six Books of Euclid : with a ...

John Playfair - Euclid's Elements - 1849 - 332 pages
...them : and EF is parallel to AB ; therefore AB is at right „ angles (7. 2. Sup.) to the plane HGK. For the same reason, CD is likewise at right angles...lines are at right angles to the same plane, they are paralK. -D lei (6. 2. Sup.) to one another. Therefore AB is parallel to CD. PROP. IX. THEOR. If two...

## Scholarship examinations of 1846/47 (-1853/54).

Bengal council of educ - 1852 - 348 pages
...base double of the third angle : and deduce the expression for sin 36°. 3. If two straight lines be at right angles to the same plane they are parallel to one another. 4. Chords of a circle pass through the middle point of a fixed chord, prove that the straight line...

## Elements of Geometry: Containing the First Six Books of Euclid, with a ...

Euclid, John Playfair - Geometry - 1853 - 336 pages
...through them : and EF is parallel to AB ; therefore AB is at right angles (7. 2. Sup.) to the plane HGK. For the same reason, CD is likewise at right angles...Therefore AB, CD are each of them at right angles H to the plane HGK. But if two straight lines are at right angles to the same plane, they are paralK....

## The Elements of Euclid, with many additional propositions, and explanatory ...

Euclides - 1855 - 230 pages
...therefore AB is at right angles to the plane HGK (c): for the H 0) 1.11. (6) XI. 4. (c) XI. 8. (rf) XI. 6. same reason, CD is likewise at right angles to the...to the same plane, they are parallel to one another (d); therefore AB is parallel to CD. PROPOSITION X. THEOREM.—If two straight lines (AB, BC) meeting...