1. 30 cm
2. 80 cm
3. 6 cm
(For each of questions 2 and 3 a solution which quotes two
possible results is acknowledged only if it indicates which
of the two is the feasible one.)
Notes
1. AM = BM
So XA = YM = 12
AM2 = XM2 + XA2 = 81 + 144 = 225 etc.
2. Centre (r,r) is distance r from (16,8)
So (r-16)2 + (r-8)2 = r2, etc
Solving, r = 40
(or 8, which is too small for a table).
3. Similarly, (r-1)2 + (r-4)2 + (r-5)2 = r2
Solving, r = 3
(or 7, which is too big for a tennis ball)
THIS MONTH'S QUIZ
A coin of diameter 2 cm is thrown onto a chess board whose squares have sides of length 4 cm. Assuming the coin lands well clear of the edge of the board, find the following probabilities:
1. That the coin lies wholly within one square,
2. That the coin lies partly in just two squares,
3. That the coin lies partly in just three squares.