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Option 1 : 314 cm2

Given:

Lateral surface area of a cube = 420 cm2 less than the lateral surface area of a cylinder. 

Height of cylinder = 2R cm

Radius = R cm

The radius of circle = (R + 3) cm

Formula used:

Lateral surface area of cube = 4a2

Lateral surface area of cylinder = 2πrh

Area of circle = πr2

Calculation:

According to the question

⇒ 4R2 = 2πR × 2R – 420

⇒ 4R2 = 22/7 × 4R2 – 420

⇒ 4R2(22/7 – 1) = 420

⇒ 4R2(22 – 7)/7 = 420

⇒ 4R2(15/7) = 420

⇒ 60R2/7 = 420

⇒ R2/7 = 7

⇒ R2 = 49

⇒ R = 7 cm

Now,

​The radius of circle = (R + 3) = (7 + 3) = 10 cm

Area of circle = πR2

⇒ 22/7 × 10 × 10 cm2

⇒ 2200/7 cm2

⇒ 314.28 cm2 ~ 314 cm2

∴ The required value of circle is 314 cm2.

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