Grades 9-10 Video Solutions 2026-2026_9-10

2026_9-10_22

Video Transcription

Video Summary

The perimeter is <strong>D, 180 minus 2D</strong>.

Reason: the 9 center-to-center distances to the large circle sum to <strong>D</strong>, and since each small circle’s radius is <strong>10 -</strong> that distance, the sum of the 9 radii is <strong>90 - D</strong>. The shaded polygon includes each radius twice, so its perimeter is:

<strong>2(90 - D) = 180 - 2D</strong>.