Answer: 18.6 units Step-by-step explanation: A rectangle is a four sided shape with 4 perpendicular angles. It has two pairs of parallel sides which are equal in distance: width and length. A diagonal can be drawn between opposite corners that splits the triangle into two equal right triangles. The distance of this diagonal is found using the Pythagorean Theorem a² + b² = c². In the rectangle a = 11 and b = 15. Substitute these values and simplify using a square root operation. 11² + 15² = c² 121 + 225 = c² 346 = c² √346 = c 18.6= c