In triangle ABC, the angle A is 14 °, the outside angle at the vertex B is 91 °. Find the corner C.

It is known that the outer angle of a triangle is equal to the sum of two angles that are not adjacent to it.
Using this property, we have:
∠В = ∠ВАС + ∠АСВ;
∠АСВ = ∠В – ∠ВАС = 91 ° – 14 ° = 77 °.
Answer: The angle C of this triangle is 77 °.

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