PSLEBilly had 3.9 m of thread. He used some of it to make the figure as shown.
- How much of the thread did Andy use to make the figure? Leave your answer in the simplest form in terms of r.
- If r = 17, how much of the thread was not used to make the figure? Leave your answer in meters.
(a)
Total length of thread used
= r + r + r + (2r - 10) + (r + 14)
= r + r + r + 2r + r - 10 + 14
= (6 r + 4) cm
(b)
1 m = 100 cm
3.9 m = 390 cm
Total length of thread used if r = 17
= 6 r + 4
= 6(17) + 4
= 102 + 4
= 106 cm
Total length of thread not used
= 390 - 106
= 284 cm
1 cm = 0.01 m
284 cm = 2.84 m
Answer(s): (a) (6r + 4) cm; (b) 2.84 m