22 Feb 2013
Prize Maths Quiz: Five Circles in a Triangle (PMQ7)
To end a week of geometry problems, it is no surprise that PMQ7 is also a geometric puzzle.
The diagram shows five circles, each with integer radius, all touching the base of the large triangle. The four smaller circles all touch their two neighbouring circles, with the large circle touching all four. The two sides of the triangle each touch two of the circles.
Let the radii of the circles be a, b and c, such that a > b > c.
Given that c has a length of 4 units, find the area of the large triangle. You may leave it as an exact solution.
As always, I would like to see a method. As an interim solution, find the radii of all three circles.
How to Enter
Send your complete solution by email to [competition closed - email removed]. This email address shall be removed after the competition closes to avoid spam. This PMQ7 competition closes on Sunday 24 February at 23:59 GMT.
The prizes for this PMQ7 are 3 free places in our Online Classroom for 2 months. The very first correct solution will receive a prize plus two others randomly selected from all the other correct answers. The email time stamp shall determine the order of entries received.
Look at the expanded rules on our PMQ page.
Anybody can enter our Prize Maths Quiz; adults and students.
Use the official server clock in the right column to avoid late entries.
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Enjoy the challenge!
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