An open cone with base radius 28cm and perpendi... - WAEC Mathematics 2013 Question
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 option: a
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
= 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
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