Non-right-angled triangles and some practical applications 213
B
C
A
408
Figure 23.20
4. From Figure 23.20, determine how far C
moves, correct to the nearest millimetre, when
angle CAB changes from 40 ◦ to 160 ◦ , B
moving in an anticlockwise direction.
5. 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.
6. Calculate, correct to 3 significant figures, the
co-ordinates x and y to locate the hole centre
at P shown in Figure 23.21.
100 mm
1168
1408
P
x
y
Figure 23.21
7. An idler gear, 30 mm in diameter, has to be
fitted between a 70 mm diameter driving gear
and a 90 mm diameter driven gear, as shown
in Figure 23.22. Determine the value of angle
θ between the centre lines.
90 mm
dia
30 mm
dia
70 mm
dia
␪
99.78 mm
Figure 23.22
8. 16 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.