 The acute angle which a straight line makes with its projection upon a plane is the least angle which it makes with any line of the plane.  A Text-book of Geometry - Page 270by George Albert Wentworth - 1894 - 437 pagesFull view - About this book
 | Wooster Woodruff Beman, David Eugene Smith - Geometry, Solid - 1900 - 160 pages
...coplanar ? PROPOSITION XIII. 348. Theorem. The acute angle which a line makes with its own projection on a plane is the least angle which it makes with any line in that plane. Given the line AB, cutting plane P at 0, A'B' the projection of AB on P, and XX' any... | |
 | Thomas Franklin Holgate - Geometry - 1901 - 462 pages
...straight line to another which does not meet it. 444-449] LINES AND PLANES IN SPACE PROPOSITION XX 449. The acute angle which a straight line makes with its own projection upon a plane is the least angle it makes with any line of that plane. Let AB be any straight line oblique to the plane L, and let BC... | |
 | George Albert Wentworth - Geometry, Solid - 1902 - 246 pages
...plane is the PROPOSITION XXIV. THEOREM. 567. The acute angle which a straight line makes ioith its projection upon a plane is the least angle which it...other line drawn through A in the plane. To prove that Z- BAC is less than Z BAD. Proof. Take AD equal to AC, and draw BD. In the A BAC and BAD, BA =... | |
 | George Albert Wentworth - Geometry - 1904 - 496 pages
...a plane is the PROPOSITION XXIV. THEOREM. 567. The acute angle which a straight line makes with its projection upon a plane is the least angle which it...other line drawn through A in the plane. To prove that Z SAC is less than Z. BAD. Proof. Take AD equal to AC, and draw BD. In the A BAC and BAD, BA =... | |
 | Fletcher Durell - Geometry, Solid - 1904 - 232 pages
...(Art. 559). PROPOSITION XXII. THEOREM 567. The acute angle which a line makes with its projection on a plane is the least angle which it makes with any line of the plane through its foot. p- ' Given line AB meeting the plane MN in the point B, BC the projection of AB on... | |
 | Fletcher Durell - Geometry - 1911 - 553 pages
...(Art. 559), PROPOSITION XXII. THEOREM 587. The acute angle which a line makes with its projection on a plane is the least angle which it makes with any line of the plane through its foot. 2L. Given line AB meeting the plane MN in the point J5, $0 the projection of AB on... | |
 | Yale University. Sheffield Scientific School - 1905 - 1074 pages
...SOLID GEOMETRY JUNE, 1907 1. What is meant by the projection of a line on a given plane? Show that the acute angle which a straight line makes with its...plane is the least angle which it makes with any line in that plane. 2. State and prove the theorem concerning the lateral area of a regular pyrnrfiid. What... | |
 | William Chauvenet - 1905 - 336 pages
...PROPOSITION XVIII. The projection of a straight line upon a plane is a straight line. PROPOSITION XIX. The acute angle which a straight line makes with its own projection upon a plane is the least angle it makes with any line of that plane. PROPOSITION XX. The sum of any two face angles of a triedral... | |
 | Education - 1911 - 946 pages
...oblique to a plane, one and only one plane can be passed perpendicular to the given plane. [Ell.] 12. The acute angle which a straight line makes with its own projection on a plane is the least angle which it makes with any line of the plane. [013.] 13. Two right prisms... | |
 | Isaac Newton Failor - Geometry - 1906 - 431 pages
...the plane. 294 PROPOSITION XXIII. THEOREM 577 The acute angle which a straight line makes with its projection upon a plane is the least angle which it makes with any line in the plane. HYPOTHESIS. BC is the projection of AB upon the plane MN, and BD is any other line in... | |
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