Basic Engineering Mathematics, Fifth Edition

Non-right-angled triangles and some practical applications 213

B

C

A

408

Figure 23.20

4. From Figure 23.20, determine how farC
   moves, correct to the nearest millimetre,when
   angleCABchanges from 40◦ to 160◦, B
   moving in an anticlockwise direction.


5. A surveyor standing W 25◦Sofatowermea-
   sures 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 ′.Determinetheheight of thetower if the
   distance between the twoobservationsis75m.


6. Calculate, correct to 3 significant figures, the
   co-ordinatesxandyto locate the hole centre
   atPshown in Figure 23.21.

100 mm

1168 1408

P

x

y

Figure 23.21

7. An idler gear, 30mm 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
   θbetween 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.