T H E E L E M E N T S |
Book I Proposition 45 | |
Then, since each to the angles FKH, GHM is equal to the angle E, the angle FKH is also equal to the angle GHM. [C.N.1] Let the angle KHG be added to each; therefore the angles FKH, KHG are equal to the angles KHG, GHM. But the angles FKH, KHG are equal to two right angles [I.29]; therefore the angles KHG, GHM are also equal to two right angles. Thus, with a straight line GH, and at a point H on it, two straight lines KH, HM not lying on the same side make adjacent angles equal to two right angles; therefore KH is in a straight line with HM. [I.14] |
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