The essentials of descriptive geometry . be revolved into the plane of the axis PQ. The revolutionmay be accompKshed as indicated above or by working the Fig. 40. problem without the use of the secondary H or V plane. In thefigure the line MN has been revolved into the plane PQ directly,M falls at a point whose elevation is m, m being a distancefrom the axis equal to the hypotenuse of a triangle whose base isthe distance of m to the axis, or my, and whose altitude is thedistance M is from the plane of the axis, or mx. 36. To revolve a plane into H or V about the H or V a point on
The essentials of descriptive geometry . be revolved into the plane of the axis PQ. The revolutionmay be accompKshed as indicated above or by working the Fig. 40. problem without the use of the secondary H or V plane. In thefigure the line MN has been revolved into the plane PQ directly,M falls at a point whose elevation is m, m being a distancefrom the axis equal to the hypotenuse of a triangle whose base isthe distance of m to the axis, or my, and whose altitude is thedistance M is from the plane of the axis, or mx. 36. To revolve a plane into H or V about the H or V a point on the trace, as A on the trace tT in Fig. 40, 42 ESSENTIALS OF DESCRIPTIVE GEOMETRY Revolve this point into H about tT as an axis as in Article this revolved position, Ah, and the point T on the G. the line tnT. This will be the revolved position of the Vtrace as it lies on H and tnTt is the revolved position of theplane T. To revolve the plane into V a point on the H trace should betaken and the V trace used as an Fig. 41. 37. To find the plan and elevation of a line in a plane when therevolved position of the Kne and plane are given. In Fig. 41 is shown a plane T and a Hne MN in the plane T asthey lie revolved into the H plane at tTtn and MhNh. To findthe actual position of the traces and the plan and elevation ofthe Une assume Ph, the revolved position of a point on the re-volved V trace. P, since it is on the V trace, will he in V and itsplan view therefore lies on the G. L. Through Ph draw a per- REVOLUTION OF POINTS 43 pendicular to Tt, since Tt must be the axis of revolution, andextend it to the G. L. at p. p, then, is the plan of a point P onthe V trace, and the elevation will be at p which is below theG. L. a distance equal to ox. To find ox lay off px equal to opu-ox then is the base of the triangle whose hypotenuse is px, oroPh- Draw tT through T and p and it will be the true positionof the V trace and tTt will represent the true position of th
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Keywords: ., bookcentury1900, bookdecade1910, bookidcu3192400462, bookyear1915
