An angle opposite the larger side of a triangle with sides 4 cm. 7 cm. 9 cm, what kind of angle?

c² = a² + b² – 2 a * b * cos C, where a, b and c are the sides of the triangle, <C is the angle lying

against the larger side;

a = 4 cm; b = 7 cm; s = 9 cm;

cos C = (a² + b² – c²): 2 a * b = (16 + 49 – 81): 2 * 4 * 7 ≈ – 0.285714;

<C ≈ 106.6 ° – dull;



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