# ABC triangle, find angle C if angle A and B = 40 degrees.

July 27, 2021 | education

| Consider a triangle ABC.

In the indicated triangle, the values of two angles are given.

These are corners A and B.

In order to find out what the third angle is, recall the rule according to which the sum of all the angles of a triangle is 180 °.

Now let’s write down equality.

A + B + C = 180 °.

By condition, the angle A is equal to 40 °. Angle B is also 40 °.

In order to find the third angle, we substitute the values of the angles A and B into the above equality.

40 ° + 40 ° + C = 180 °.

80 ° + C = 180 °.

C = 180 ° – 80 °.

C = 100 °.

Answer: 100 ° is the value of the angle C.

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