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Answer

CD = R + r + r + R = 14 cm

2R + 2r = 14

2(R + r) = 14

R + r = 7 cm

AD = BC = (R + r) = 7 cm

 

Perimeter of big semicircle (2 × quarter circle)

½ × 2πR = πR

 

Perimeter of small semicircle → ½ × 2πr = πr

 

Total Perimeter → 7 + 14 + 7 + πR + πr = 28 + π(R + r) = 28 + 22/7 × 7 = 50 cm

 

0 Replies 0 Likes ✔Accepted Answer

Drawing a perpendicular line through the centre of the semicircle, AD = BC = 7 cm.
total perimeter of the shaded part ——- 7 + 14 + 7 + (1/2) x (22/7) x 14 = 50

Ans : 50 cm.

1 Reply 1 Like

sorry I still dun get it

how to know the radius of the quadrant and the semicircle?

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As the question asks for the total perimeter of the shaded parts, instead of using the radii of the quadrant and the semicircle, we could use their diameters, which totals 14cm,  instead. 🙂

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