The outer angles at the vertices M and N of the triangle KMN are 100 ° and 110 °. Find ∠MKN.

1. Let us determine the value of the internal angle at the vertex M, if its external value is known from the condition.

180 – 100 = 80 °.

2. Since the internal angle N is adjacent to the external one, we recognize its degree measure.

180 – 110 = 70 °.

3. How many degrees is the MKN angle?

180 – (80 + 70) = 30 °.

Answer: 30 °.



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