What is the measure of the radius of the circle that circumscribes a triangle whose sides measure 9, 40 and 41?  Answers
A) 6 B) 4 C) 24.5 D) 20.5 E) 12.5
Explanatory Answer   9, 40 and 41 is Pythagorean triplet. So, the triangle is right angled.   Key property about right triangles   In a right angled triangle, the radius of the circle that circumscribes the triangle is half the hypotenuse.   In the given triangle, the hypotenuse = 41.   Therefore, the radius of the circle that circumscribes the triangle = 41/2= 
<gadget id="calculator">41/2</gadget>
<output>41/2 = around 20.5</output>
20.5 units.   Choice 20.5
<result>D</result>
What is the measure of the radius of the circle that circumscribes a triangle whose sides measure 9, 40 and 41?