An open cone with base radius 28cm and perpendicular height 96cm was stretched to form sector of a circle. calculate the arc of the sector (Take (pi = frac{22}{7}))
-
A.
8800cm2 -
B.
8448cm2 -
C.
4400cm2 -
D.
4224cm2
Correct Answer: Option A
Explanation
L2 = 962 + 282
= 9216 + 784
= 10000
L = (sqrt{10000})
= 100cm
curved surface area = (pi r l)
= (frac{22}{7} times 28 times 100)
= 8800cm2
area of cone = area of sector
area of sector = 8800cm2