In a triangle ABC AB = 2cm, AC = 2cm, cosA = 1/8. Find BC.
| July 15, 2021 | education
AB lies opposite angle C, AC – opposite angle B, BC – opposite angle A.
Angle A is formed by sides AB and AC.
In accordance with the cosine theorem, we write:
BC ^ 2 = AB ^ 2 + AC ^ 2 – 2cosA * AB * AC = 2 ^ 2 + 2 ^ 2 – 2 * 1/8 * 2 * 2 = 8 – 1 = 7 cm ^ 2.
BC = √ (7 cm ^ 2) = √7 cm
Answer: √ 7 cm.
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