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Q: If two angles of a triangle measure 60º and 80º respectively, then the measure of the third angle of this triangle is:
  • A. 50º
  • B. 70º
  • C. 60º
  • D. 40º
Correct Answer: Option D - Sum of all three angles of a triangle be 180°. According to the question, Third angle of a triangle = 180º – (80º + 60º) = 180º – 140º = 40º
D. Sum of all three angles of a triangle be 180°. According to the question, Third angle of a triangle = 180º – (80º + 60º) = 180º – 140º = 40º

Explanations:

Sum of all three angles of a triangle be 180°. According to the question, Third angle of a triangle = 180º – (80º + 60º) = 180º – 140º = 40º