Sec 2 Maths (Mensuration)

Dixon999 SG

A paper weight has the shape of a half-cone with a diameter of 10 cm and a vertical height of 15 cm. Using the information, calculate the following: [Take pi=3.142]

(a) total volume of the paper weight

(b) curved surface area of the paper weight

Juz like 2 double check whether my ans is correct...

(a) 196 cm^{3 (3 sig fig)} (b) 124 cm^{2 (3 sig
fig)}

Craappiboy SG

a correct

b wrong.

Dixon999 SG

For (b), this is how i solve:

formula for curved surface area of half-cone = 0.5 x pi x r x l

where r= 5,

l= square root of 250 (using pythagoras' theorem to obtain value of slant height)

pls comment...

eagle SG

For (b), this is how i solve:

formula for curved surface area of half-cone = 0.5 x pi x r x l

where r= 5,

l= square root of 250 (using pythagoras' theorem to obtain value of slant height)

pls comment...

you need to include the base area (half of a circle) and one cross sectional area as well

Dixon999 SG

the qn onli ask 2 calculate curved surface area not total suface area

eagle SG

the qn onli ask 2 calculate curved surface area not total suface area

oh ya, then in that case, you are right.