116 Higher Engineering Mathematics
For the position shown determine the length
of AC and the angle between the crank and
the connecting rod.
[40.25 cm, 126 ◦ 3 ]
40Њ
A
B
C
Figure 11.42
6. From Fig. 11.42, determine how far C moves,
correct to the nearest millimetre when angle
CAB changes from 40 ◦ to 160 ◦ , B moving in
an anticlockwise direction.
[19.8 cm]
7. A surveyor, standing W 25 ◦ S of a tower measures the angle of elevation of the top of the
tower as 46 ◦ 30 . From a position E 23 ◦ S from
the tower the elevation of the top is 37 ◦ 15 .
Determine the height of the tower if the
distance between the two observations is 75 m.
[36.2 m]
8. An aeroplane is sighted due east from a radar
station at an elevation of 40 ◦ and a height
of 8000 m and later at an elevation of 35 ◦
and height 5500 m in a direction E 70 ◦ S. If
it is descending uniformly, find the angle of
descent. Determine also the speed of the aeroplane in km/h if the time between the two
observations is 45 s.
[13 ◦ 57 , 829.9 km/h]
9. Sixteen holes are equally spaced on a pitch circle of 70 mm diameter. Determine the length of
the chord joining the centres of two adjacent
holes.
[13.66 mm]