In a triangle ABC, c = 90 degrees, AC = 8√3, sine a = 1/8. Find AB.
February 23, 2021 | education
| Knowing the sine of the angle BAC, we determine the cosine of this angle.
Sin2BAC + Cos2BAC = 1.
Cos2BAC = 1 – Sin2BAC = 1 – (1/7) 2 = (49 – 1) / 49 = 48/49.
CosВАС = √ (48/49) = 4 * √3 / 7.
CosBAC = AC / AB.
AB = AC / CosBAC = 8 * √3 / (4 * √3 / 7) * = 56/4 = 14 cm.
Answer: The length of the AB side is 14 cm.
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