Square P is inscribed in circle Q. If the perimeter of P is 40, what is the circumference of Q? Choose one.
A) 11√ 2π  B) 10√ 2π  C) 9√ 2π  D) 8√ 2π  E) 7√ 2π
square forms two right angled triangles.   Any time we have a right angle triangle inside a circle, the hypotenuse is the diameter.   hypotenuse here = diagonal of the square = 10 sqrt(2) = diameter   =&gt; radius = 5 sqrt(2)   Circumference of the circle = 2pi r = 10 pi sqrt(2)   Answer is 10√ 2π.
<result>B</result>
Square P is inscribed in circle Q. If the perimeter of P is 40, what is the circumference of Q?