Calculate the angle A of triangle C = 70 degrees B = 40 degrees.

By theorem: the sum of all the angles of a triangle is 180 degrees.

A + B + C = 180 °.

Let’s find the sum of two known angles B and C:

40 + 70 = 110 °.

From the sum of all the angles of the triangle, subtract the sum of the angles B and C and find what the angle A is equal to.

180 ° – 110 ° = 70 °.

Answer: Angle A is 70 °.

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