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
Correct answer is A
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)