Answer: {42, 56, 69}Step-by-step explanation:For repetitive calculations, a spreadsheet or calculator can relieve the tedium. We're asked to evaluate the Pythagorean relation for different number sets. Here, we need to find the set of numbers such that ... c² ≠ a² +b² . . . . . not a right triangleThis is equivalent to ... a² +b² -c² ≠ 0which is the formula we used in the graphing calculator shown in the attachment.The lengths {42, 56, 69} will not form a right triangle._____Additional commentThe difference of squares form used in f(x) gives a value that is related to the cosine of the largest angle in the triangle: cos(θ) = f(a, b, c)/(2ab)The sign of the value of f(x) is positive for acute triangles, negative for obtuse triangles. The largest angle in {42, 56, 69} is about 88.3°.