Question

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Answer 1

Answer:

BC ≈ 19.4 cm

Step-by-step explanation:

Using the cosine ratio in the right triangle

cos71° = $\frac{adjacent}{hypotenuse}$ = $\frac{AB}{BC}$ = $\frac{6.3}{BC}$ ( multiply both sides by BC )

BC × cos71° = 6.3 ( divide both sides by cos71° )

BC = $\frac{6.3}{cos71}$ ≈ 19.4 cm ( to 3 significant figures )

Answer 2

Answer:

BC= 19.4 (3s.f.)

Step-by-step explanation:

Since Angle CAB = 90

Therefore Angle ACB = 180° - 90° -71° = 19°

Using Sine Rule,

6.3cm/Sin(19°) = BC/Sin(90°)

BC= 19.350787697

= 19.4 cm (3 S.F.)