If you plot the coordinates on a piece of graph paper your answer would come out too (1,-8)
Radian: is the standard unit of angular measure, used in many areas of mathmatics.
degree: is a measuement of plane angle, defined by representing a full rotation as 360 degrees.
Both are two units for measuring angles. There are at least four such units, but degrees and radians are most likely to encounter high school and college.
It looks like the length of a and b should be the same. You can use the Pythagorean theorem (only works with right triangles):
a² + b² = c² (c is the hypotenuse or the longest side of the triangle, a and b are the other side lengths of the triangle)
a² + (4)² = (5)²
a² + 16 = 25
a² = 9
a = 3
a and b have a length of 3
