Answer for Day 7 Math Problem

6.75π square meters 🎯

21.21 meters² 🎯

Any of the two answers above shall be accepted.

Solution

The formula for the surface area of a sphere is 4πr². Since a hemisphere is just the half of a sphere, its (outer) surface area is 2πr². Since the hollow part of the hemisphere is covered, there is an additional πr² on the surface area of the hemisphere. Therefore, we just need to get the radius by halving the diameter, then substituting it to 3πr² to get the final answer.

• radius = (diameter) / 2 = 3 / 2 = 1.5
• surface area = 3 * π * 1.5² = 6.75π square meters or approximately 21.21 meters²

Winner: @minus-pi 🏅

1 HIVE has been sent to @minus-pi's Hive account. 💰

Sorry for posting the problem late! I know that most of the participants are in locations where it is almost midnight at the official time of 03:00 P.M. (UTC +8). This problem came from one of my draft problems which I archived because I liked more the other problems I prepared. 😅

• @jfang003's answer would have been correct, if he didn't forget to divide the diameter by 2 first!
• I don't know how @appukuttan66 got his answer.

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