Question

Which of the following sets of numbers could not represent the three sides of a triangle?
Answer
Multiple Choice Answers
left curly bracket, 7, comma, 10, comma, 15, right curly bracket{7,10,15}
left curly bracket, 6, comma, 15, comma, 19, right curly bracket{6,15,19}
left curly bracket, 5, comma, 15, comma, 20, right curly bracket{5,15,20}
left curly bracket, 4, comma, 12, comma, 15, right curly bracket{4,12,15}

Answer 1

{5, 15, 20}

Because 5 + 15 = 20, the sum of two sides equals the third, so they cannot form a (nondegenerate) triangle — the triangle inequality requires each pair-sum be strictly greater than the third.