PSLEIan had 3.4 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 = 15, 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 - 8) + (r + 18)
= r + r + r + 2r + r - 8 + 18
= (6 r + 10) cm
(b)
1 m = 100 cm
3.4 m = 340 cm
Total length of thread used if r = 15
= 6 r + 10
= 6(15) + 10
= 90 + 10
= 100 cm
Total length of thread not used
= 340 - 100
= 240 cm
1 cm = 0.01 m
240 cm = 2.4 m
Answer(s): (a) (6r + 10) cm; (b) 2.4 m