Observation

 

Many of the candidates attempted this question and performed fairly well

In solving this question, the true lengths of the other two sides were constructed, then of the true shape of the triangular lamina.

 

There are two basic methods that can be used to solve this problem, which are:
Direct method

 This method invloves working on one of the views.

None of the candidates used this method.
(A) COPYING THE GIVEN VIEWS

Candidates were expected to:

(i)draw the X – Y axis;  

(ii)draw the plan;            

(iii)project from the plan to the front elevation;

(iv)draw the front elevation;

(v)draw neatly.

               

(B)CONSTRUCTING THE TRUE SHAPE OF THE LAMINA

Candidates were expected to:

(i) extend line ba to G;  

(ii) draw line SH perpendicular to Gb to pass through point C;

(iii) draw line Jc parallel to line Gb;        

(iv)draw TD perpendicular to line Gb; 

(v)transfer the altitude h of triangle ABC on line Jc as MN;

(vi) use TM as radius to describe arc MP at T to locate point P;

(vii)      draw a line from point P parallel to line Gb to locate point C1, on line SH;  

(viii) join lines bc1 and ac1 to obtain the true shape of the triangular lamina abc1;

(ix) draw neatly. 

 

(C)MEASURING AND STATING THE LENGTH OF THE THREE SIDES

Candidates were expected to state the lengths of the three sides as follow:

(i)         ab  =  71+ 1,    (ii)  ac, = 48+ 1     (iii)   bc,  =  66  +

The solution is shown below:

DIRECT METHOD

 

INDIRECT METHOD: Involves finding the true length of the other two sides.  This can be done using rebate method, triangulation method or auxiliary method.Many of the candidates used this method.

(A)COPYING THE GIVEN VIEWS

Candidates were expected to:

(i)         draw the X – Y axis;              
(ii)        draw the plan;
(iii)       project from the plan to the front;

(iv)draw the front elevation;  

(v)draw neatly.   

 

(B)CONSTRUCTING THE TRUE SHAPE OF THE LAMINA

Candidates were expected to:
(i)         draw the horizontal line at c;

(ii)rabate line AC  to locate point M on plan;     

(iii)project from point M to locate point C11; 

(iv)join line ac11 to obtain the true length of line AC; 

(v)rabate line BC to locate point T on plan;       

(vi)project from point T to locate point c1;     

(vii)join line bc1 to obtain the true length of line BC;  

(viii)construct the true shape of the lamina using true lengths of lines bc1, ac11 and                                                   

(ix)draw neatly.   

 

(C)MEASURING AND STATING THE LENGTHS OF THE THREE SIDES

Candidates were expected to state the lengths of the three sides as follow:

(i)ab =  71 +  ,      (ii)      ac1 = 48 +  1  and bc’  =  66  +  1 

The solution is shown below:

     

INDIRECT METHOD