The radius of the smallest circle containing the symmetric figure composed of the three squares shown at the right is:

- √2
- √1.25
- 1.25
- 5√17

16 - none of these

We’ll design a circle that passes through A, B, C, and D. Its center will be at O, on the line bisecting the symmetric figure, and its radius will be *x*.

We see that *x* is the hypotenuse of two right triangles, OEB and OFC. Let OF = *t*. Then *t*) = 2 – *t*

We see that *x* is approximately 1.29, which is not too different from answer choice (c), but (d) is the exact answer.