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If the radius of a sphere is increased by 2 cm, then its surface area increases by 704 cm². Using π = 22/7, find the radius of the sphere before the increase

A14 cm

B15 cm

C16 cm

D13 cm

Answer:

D. 13 cm

Read Explanation:

4π(r+2)24πr2=7044 \pi (r+2)^2-4\pi r^2=704

4π(r2+4r+4r2)=7044\pi(r^2+4r+4-r^2)=704

4×227(4r+4)=7044\times \frac{22}{7} (4r+4)=704

4r+4=564r+4=56

4r=524r=52

r=52/4=13r=52/4=13


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