Question 2
Two views of a triangular lamina PQR are shown in Fig. 2. Copy the given views and determine:
(a)
(i) the true shape of the lamina;
(ii) angle to the horizontal plane.
(b) Measure and state the lengths of its sides.
Observation
This question invloves finding the true shape of a triangular lamina and stating its angle of inclination to the horizontal plane.
Many candidates attempted this question and their perfomance was fairly okay.
Candidates were expected to do the following:
TRIANGULAR LAMINA
A. COPYING THE GIVEN VIEWS
(i) draw the X-Y axis;
(ii) draw the plan correctly;
(ii) draw the front elevation.
B. DRAWING THE FIRST AUXILIARY ELEVATION
(i) draw the horizontal line from R1 to T1in the front elevation;
(ii) project down from T1 to T in the Plan;
(iii) join lines R to T and produce ;
(iv) draw lines from Q and P parallel to line RT produced and extending the lines;
(v) draw X1 –Y1 axis perpendicular to the parallel lines drawn from points
P, Q and R ;
(vi) locate points Q2, R2 and P2 as corresponding distances of Q1, R1and P1 from X – Y axis;
(vii) draw lines Q2, R2 and P2 as the first auxiliary elevation edge view of the lamina.
C (I) DRAWING THE SECOND AUXILLIARY ELEVATION ( TRUE SHAPE OF THE TRIANGULAR LAMINA)
(i) draw X2 _ Y2 axis parallel to line Q2 P 2;
(ii) draw perpendicular lines from points Q2,R2 and P2;
(iii) locate pointsQ3,R3 and P3 on X2 –Y2 axis as corresponding distances of points Q, R, and P from X1 –Y1 axis;
(iv) join the points Q3,R3 and P3 to obtain the true shape of the triangular lamina.
C (II) measure and state the angle of inclination to the horizontal plane HP as angle Q2 X1 Y1= 480 ±10.
D measure and state the lengths of sides as P^3 Q^3 and R^3 P^3.