Find the value of l in the frustrum above - JAMB Mathematics 1999 Question
A
5cm
B
6cm
C
7cm
D
8cm
correct option: a
ΔABE and ΔACD are similar
6x = 3(x+4)
6x = 3x + 12
3x = 12
x = 4
In ΔACD; L2 = (4+4)2 + 62
= 82 + 62
= 64 + 36
= 100
L =
√ 100
= 10cm
In ABE, AE2 = 42 + 32
= 16 + 9
= 25
AE = 5cm
∴L = 10 - 5
= 5cm
| ∴ | x |
| |||
| x+4 |
6x = 3(x+4)
6x = 3x + 12
3x = 12
x = 4
In ΔACD; L2 = (4+4)2 + 62
= 82 + 62
= 64 + 36
= 100
L =
√ 100
= 10cm
In ABE, AE2 = 42 + 32
= 16 + 9
= 25
AE = 5cm
∴L = 10 - 5
= 5cm
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