Question

Find the length of the arc shown in red. Leave your answer in terms of π

Answer 1

• 1.5π

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The arc in red has same measure as the opposite arc of 30°, since vertical angles are congruent.

Use arc length formula:

• s = 2πr(α/360), where α is the arc measure in degrees

Substitute 9 m for r and 30° for α:

• s = 2π(9)(30/360) = 18π/12 = 1.5π meters