In a scalene triangle the longest side is opposite the angle with the largest measure true of false?

True.

In any triangle, the longest side is always opposite the largest angle; the shortest side is always opposite the shortest angle; and the middle length side is always opposite the middle size angle.

In an isosceles triangle, there is no middle length side; and the two sides of equal length are opposite the angles of equal size.

In an equilateral triangle, all sides are the same length, as are all the angles.