Surface area of a hemisphere
The surface area of a hemisphere is the curved surface plus the circular base when the whole outer surface is asked for.
Practice This ConceptMain explanation
Teacher explanation
A hemisphere is half of a sphere. It has one curved half-spherical surface and one flat circular base. If the question asks for total surface area, both parts are counted, so the formula becomes 3πr². If only the curved part is asked, then 2πr² is used.
Example
A hemisphere of radius 7 cm has total surface area 3πr² = 3π × 49 = 147π cm², which is 462 cm² when π = 22/7.
Simple analogy
Hemisphere total means curved part plus base.
Common confusion
Students often use only 2πr² and forget that the circular base must also be included for total surface area.
Exam tip
Read the wording carefully: curved surface only means 2πr², but total surface area means 3πr².
Answer writing and exam use
1-mark use
Write the exact meaning of surface area of a hemisphere in one clean line.
2-mark use
Define surface area of a hemisphere and add one example or condition.
3-mark use
Explain surface area of a hemisphere, show the method or example, and mention the common mistake.
Practice this concept with focused MCQs
Open the concept quiz intro first, review the test details, and then start a focused MCQ set from this concept only. Instant score and answer review are live now.
Help improve this page
Found something confusing, incorrect, or missing?