Three circles and the lines and touch as shown. The distance between the centres of the smallest and the biggest circles is 16 times the radius of the smallest circle.
What is the size of ?
Select one option, then click Submit.
45^\circ
60^\circ
75^\circ
90^\circ
135^\circ
Select an option, then submit.
Sign in or create an account to reveal answers, view the solution, and save your progress. Create a free account to unlock practice and keep track of your work.
Senior Mathematical Challenge 2011 (2011)
One puzzle per day. Cryptarithm, Magic Square, Summit. No sign-up required to play.
Play daily puzzle →Interactive problems and curated lessons—water pouring, magic squares, knight's tour, and more.
Browse library →See how you rank. Top solvers by problems solved correctly. Sign in to climb the ranks.
View leaderboard →Senior Mathematical Challenge 2011 (2011)