Woods, Frederick S. (Frederick Shenstone), 1864-, Bailey, Frederick H. (Frederick Harold), 1865- · Boston, New York [etc.] Ginn and Company · leaf 78
wn. Since the line passes through (— 2, 3), 3 (-2)-5 (3) + C=0, whence C = 21. Therefore the required equation is 3 x — 5 y + 21 = 0. ANGLES 61 3. Perpendicular lines. Let AB and CD (fig. 68) be two linesintersecting at right angles. Through P draw PR parallel toOX, and let RPD = </>1 and RPB… … That is, two straight lines are perpendicular when the slope ofone is minus the reciprocal of the slope of the other. This theoremmay be otherwise expressedby saying that two lines areperpendicular when the prod-uct of their slopes is minusunity. It follows that two straightlines whose equations…
Geometry, Analytic · Calculus
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