WAEC - Mathematics (2013 - No. 34)
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 \(\pi = \frac{22}{7}\))
8800cm2
8448cm2
4400cm2
4224cm2
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
= 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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