Bunuel wrote:

If the circle above has center O and circumference 18π, then the perimeter of the sector RST is

(A) 3π + 9

(B) 3π + 18

(C) 6π + 9

(D) 6π + 18

(E) 6π + 24

Attachment:

2017-11-21_1032_002.png

Perimeter of sector RST =

RST arc length + 2*(radius)

Sector RST is what fraction of the circle?

\(\frac{SectorAngle}{Circle}=\frac{60°}{360°}=\frac{1}{6}\)

Sector RST = \(\frac{1}{6}\) of the circle.

RST arc length?

\(\frac{1}{6}\) of circumference

\(\frac{1}{6}*18π = 3π\)

Radius length?

From circumference:

2πr = 18π

r = 9

Perimeter = (3π + 2*9) = 3π + 18

Answer B

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In the depths of winter, I finally learned

that within me there lay an invincible summer.

-- Albert Camus, "Return to Tipasa"