GMAT Quant Questions | Geometry #3

This GMAT quant practice question is a problem solving question in Geometry. Concept: Radius of the circle that circumscribes a triangle.

Question 3: What is the measure of the radius of the circle that circumscribes a triangle whose sides measure 9, 40, and 41?

1. 6
2. 4
3. 24.5
4. 20.5
5. 12.5

---

---

Video Explanation

---

---

Explanatory Answer | GMAT Geometry

9, 40, and 41 is a 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 = \\frac{\text{41}}{\text{2}}) = 20.5 units.

Choice D is the correct answer.