Courses
Courses for Kids
Free study material
Offline Centres
More
Store Icon
Store
seo-qna
SearchIcon
banner

The curved surface area of a right circular cone of height 15cm and base diameter 16 cm is………………………….
(a) 60πcm2(b) 68πcm2(c) 120πcm2(d) 136πcm2

Answer
VerifiedVerified
526.5k+ views
like imagedislike image
Hint: In this question the height and base diameter of a right circular cone is given. Use the direct formula for curved surface area for the right circular cone (πrl) to evaluate the required quantity.

Complete step-by-step answer:
seo images

As we know that the curved surface area (C.S.A) of the right circular cone is πrl.
Where, l = slant height of the cone.
              r = base radius of the cone.
Now it is given that the height (h) of the cone is 15 cm and the diameter (d) of the cone is 16 cm.
Now as we know that the radius (r) is half of the diameter (d).
r=d2=162=8 cm.
Now in a right circular cone slant height (l) is given as
In triangle ABC apply Pythagoras theorem we have,
l2=h2+r2
l=h2+r2
So substitute the value in the above equation we have,
l=(15)2+82=225+64=289=17 cm.
So the curved surface area (C.S.A) of the right circular cone is
 C.S.A=πrl=π(8)(17)=136π cm2.
So this is the required curved surface area (C.S.A) of a right circular cone.
Hence option (d) is correct.

Note: Whenever we face such types of problems the key point is to have the good gist of the diagrammatic representation using the information provided in the question as it helps understanding the geometry of the figure involved. It is always advisable to learn the direct formula for some of the basic conic sections like the right circular cone as it helps to save a lot of time.
Latest Vedantu courses for you
Grade 11 Science PCM | CBSE | SCHOOL | English
CBSE (2025-26)
calendar iconAcademic year 2025-26
language iconENGLISH
book iconUnlimited access till final school exam
tick
School Full course for CBSE students
PhysicsPhysics
ChemistryChemistry
MathsMaths
₹41,848 per year
Select and buy