🔍 Key Concepts

• Use the relationship between circumference and radius of a circle: C = 2πR • Recognize that the shaded region is part of a circle sector with a central angle shown as a right angle (90°) • The shaded area is the difference between the sector area and the right triangle formed by the two radii

💭 Think About

• First, use the given circumference to find the radius of the circle. What value do you get when you solve C = 2πR? • Once you know the radius, what fraction of the full circle does a 90° angle represent, and what is the area of that sector? • What is the area of a right triangle whose legs are both equal to the radius, and how does that help you get the shaded area?

✅ Before You Answer

• Be sure you correctly compute the radius from the circumference before doing any area calculations • Confirm that the central angle is 90°, so the sector is exactly one-quarter of the full circle • Carefully subtract the triangle area from the sector area and then compare your result to the multiple-choice options