Surface Areas and Volumes
NCERT Exemplar Ch 11
CBSE_NCERT_EXEMPLAR_CH11
Grade 10
Question:
If two solid hemispheres of same base radius $r$ are joined together along their bases, then curved surface area of the new solid is:
$4\pi r^2$
$3\pi r^2$
$6\pi r^2$
$8\pi r^2$
Step-by-Step Solution
Key Concept: Joining two hemispheres along their bases forms a full sphere of radius $r$. Surface area of sphere $= 4\pi r^2$.
Stepwise Solution:
New solid is a full sphere of radius $r$. Surface area $= 4\pi r^2$. [1.0 Mark]
Marking Scheme:
• Identifying solid as sphere and stating area $= 4\pi r^2$: 1.0 Mark
Correct Answer: $4\pi r^2$
Confused by the solution? Ask the AI to explain a specific step, tell you where you went wrong, or break down the key trap in this question.