In the diagram MN is a chord of a circle KMN centre O and radius 10cm. If < MON = 140o, find, correct to the nearest cm, the length of the chord MN.

  • A 19cm
  • B 18cm
  • C 17cm
  • D 12cm
waec 2016mathematics

The correct answer is A. 19cm

From the diagram

sin 70o = \(\frac{x}{10}\)

x = 10sin 70o

= 9.3969

Hence, length of chord MN = 2x

= 2 x 9.3969

= 18.7938

= 19cm (nearest cm)

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